Error and result-code reference

Mass Forge uses explicit enums and result structures so Blueprint and C++ callers can distinguish expected gameplay outcomes from setup errors. This reference covers every public result, status, disposition, and terminal-reason enum. Treat the enum as the primary branch condition; inspect the surrounding result structure for the failed attribute, tag, policy, effect, entity, or request ID.

A rejected receipt owns no queue slot and will not complete later. An accepted request still needs execution-time validation, so retain its Request ID and handle every terminal result instead of converting the workflow to a boolean.

Handling rules

• Success, Allowed, and accepted/terminal-success states are the only general success paths. A receipt is accepted only when its Was Accepted helper is true and its request ID is positive.
• MassIsProcessing means the direct operation was attempted during a Mass processing phase. Use the corresponding queued operation when one exists; do not retry in a tight Blueprint loop.
• InvalidWorld commonly means the world-context object is null, destroyed, or belongs to a world that is shutting down. Supply a live object from the intended game world.
• InvalidEntity and stale-representation outcomes are safe failures. Re-resolve represented Actors or reacquire actorless handles instead of modifying an old index/serial pair.
• QueueFull is bounded back-pressure, not silent loss. Reduce burst size, distribute work across frames, or raise the documented project setting after measuring memory and frame cost.
• Nested results matter. For example, EntityApplicationFailed, GameplayTagFailure, PersistentEffectFailed, and TransactionFailed identify the failed layer; inspect the nested result payload for the exact cause.

Blueprint exposes expected spawn outcomes as named execution branches instead of hiding them behind a boolean. For compound gameplay operations, branch on the top-level enum first, then split the returned result struct to inspect the nested entity, attribute, tag, policy, effect, or request-ID details described below.

EMFProjectileLaunchResult

Returned immediately when a project asks the world projectile subsystem to create one actorless Mass projectile.

Value	Cause or meaning	Recommended response
Success	A projectile entity was created, initialized, and assigned a positive projectile ID.	Store the receipt if correlation is needed; render snapshots or wait for the resolved event.
InvalidWorld	The subsystem has no live world, or required Mass spawning/entity services are unavailable.	Launch from a live gameplay world after subsystem initialization and stop during teardown.
InvalidConfig	The request has no Mass Entity Config.	Assign an Entity Config containing Mass Forge Projectile Trait.
InvalidRequest	A location contains NaN, or speed, arc, release delay, or maximum lifetime is non-finite/out of range.	Sanitize authored/runtime values and keep speed/lifetime positive and delays/arcs non-negative.
MassIsProcessing	Immediate entity creation was requested while the Mass entity manager owned processing.	Queue the project-side launch until the next safe world tick; never retry inside the processor loop.
SpawnFailed	The Mass spawner did not return exactly one projectile entity.	Validate the Entity Config/archetype and world capacity, then retry only from a later safe tick.
MissingProjectileFragment	The spawned config did not contain FMF_ProjectileFragment.	Add Mass Forge Projectile Trait to the exact Entity Config supplied in the request.

EMFProjectileResolveReason

Published when an accepted Mass projectile leaves simulation.

Value	Cause or meaning	Recommended response
Impact	The point-to-point/arc flight reached its authored target and optional damage was attempted.	Use the resolved location/cue and inspect the nested Damage result before applying project-specific follow-up behavior.
LifetimeExpired	Maximum lifetime elapsed before travel reached the target.	Treat it as a miss/cleanup result; increase lifetime or reduce travel distance only when the authored design requires it.

EMFEntityResolveResult

Returned when converting a represented Actor into a generation-checked Mass Forge entity handle.

Value	Cause or meaning	Recommended response
Success	The Actor has a current, valid Mass representation.	Use the returned handle; reacquire it after representation or lifecycle changes.
InvalidWorld	The world context did not resolve to a live world.	Pass a live Actor, component, subsystem, or other object from the intended world.
InvalidActor	The Actor is null, pending destruction, or otherwise invalid.	Stop the operation and obtain a live Actor.
DifferentWorld	The Actor belongs to a different world than the selected subsystem.	Use a context object from the Actor's world and never carry handles across worlds.
RepresentationUnavailable	The world's Mass Actor representation subsystem is unavailable.	Enable/configure the required Mass representation support or use an actorless handle source.
NotRepresented	The Actor is valid but is not currently mapped to a Mass entity.	Use an ordinary-Actor adapter or wait for representation before resolving it.
StaleRepresentation	The Actor mapping returned an entity index/serial that is no longer valid.	Recreate or refresh representation; do not reuse the cleared output handle.

EMFEntitySpawnResult

Returned by the Blueprint-first single and bounded-batch entity spawn nodes.

Value	Cause or meaning	Recommended response
Success	Every requested entity was created, received its requested transform, and returned a generation-safe handle.	Store handles only for the lifetime needed and revalidate them after destruction, pooling, or world changes.
InvalidWorld	The supplied context did not resolve to a live gameplay world.	Call from an object owned by the intended game world.
InvalidEntityConfig	The Entity Config is null or invalid.	Assign a saved Mass Entity Config, preferably one generated by the Mass Forge wizard.
InvalidTransforms	The transform array is empty or contains a non-finite transform.	Supply at least one finite world transform.
SpawnLimitExceeded	One Blueprint batch requested more than 10,000 returned handles.	Split ordinary Blueprint work across bounded batches or use a measured C++ population path for larger allocations.
SpawnerUnavailable	The world does not provide the required Mass entity/spawner subsystems.	Enable the Mass dependencies and call after world subsystem initialization.
MassIsProcessing	Immediate entity creation would overlap Mass processing.	Schedule the spawn from a later safe game-thread boundary; do not retry inside a processor loop.
SpawnFailed	The Mass spawner did not create the complete requested batch.	Validate the config/archetype and world capacity; no partial output is retained.
MissingTransformFragment	The spawned archetype lacks Unreal's standard transform fragment, so placement could not be guaranteed.	Add Mass Forge Transform Trait or another trait that supplies FTransformFragment; the failed batch is destroyed.

EMFEntityDestroyResult

Returned by the Blueprint-first generation-safe destroy node.

Value	Cause or meaning	Recommended response
Success	The exact live entity generation was submitted to the Mass spawner for destruction.	Clear project-held references and reacquire any replacement entity.
InvalidWorld	The supplied context did not resolve to a live gameplay world.	Stop during teardown or supply a live context from the correct world.
InvalidEntity	The handle is unset, stale, destroyed, or belongs to another world.	Treat destruction as already complete or reacquire the intended entity; never reuse only the index.
SpawnerUnavailable	The Mass entity/spawner services are unavailable.	Call after world subsystem initialization and before teardown.
MassIsProcessing	Immediate destruction would overlap Mass processing.	Use an existing queued death/destruction path or schedule the direct destroy at the next safe boundary.

EMFAttributeAccessResult

Used by attribute reads, writes, instant-effect transactions, and queued attribute/effect receipts.

Value	Cause or meaning	Recommended response
Success	The requested read or transaction completed.	Consume the values and any clamp/operation details in the result.
InvalidWorld	No live Mass Forge world subsystem was available.	Supply a valid world context and avoid calls during world teardown.
InvalidEntity	The handle is unset, stale, or belongs to another world.	Reacquire the entity handle and verify its lifecycle.
MassIsProcessing	Direct fragment access would overlap Mass processing.	Submit the matching queued request and handle its completion event.
MissingSchema	The requested attribute domain has no configured runtime schema.	Assign the domain schema in Mass Forge project settings and rebuild the Entity Config.
UnknownAttribute	The stable attribute ID is absent from its configured schema.	Select a current schema entry or migrate the old ID deliberately.
MissingFragment	The entity archetype does not contain the required attribute fragment.	Add the Mass Forge Attributes Trait and the needed domain to the Entity Config.
InvalidMagnitude	A supplied or calculated float is NaN, infinite, or otherwise invalid.	Sanitize gameplay inputs and validate every custom calculation before submission.
MissingMagnitudeParameter	An effect requested a named context scalar that was not supplied.	Add the parameter to the effect context or remove/correct the authored parameter name.
InvalidEffect	The Instant Effect asset is null, invalid, or changed incompatibly.	Repair the asset in its authoring overview and rerun Project Health.
GameplayTagFailure	The atomic effect's tag portion could not validate or commit.	Inspect the effect's failed tag/result, trait capacity, and tag counts.
QueueFull	The bounded attribute or instant-effect queue has no free request slot.	Throttle the producer or raise the matching pending-request limit after profiling.
MagnitudeCalculationFailed	An assigned custom magnitude calculation rejected, was invalid/unloadable, recursed, or returned a non-finite value.	Inspect FailedModifierIndex and MagnitudeCalculationResponse; repair the stable calculation asset or its inputs before retrying.

EMFEffectMagnitudeCalculationResult

Returned by reusable Blueprint/C++ effect-magnitude calculation assets.

Value	Cause or meaning	Recommended response
Success	The calculation returned a finite final magnitude.	Use the returned magnitude; Mass Forge continues staging the enclosing transaction.
Rejected	Project logic intentionally refused to calculate for this context.	Inspect the stable calculation ID/reason and treat expected gameplay denial separately from setup failure.
InvalidWorld	The query has no live world or crosses world ownership.	Supply context from the same active world as the transaction.
InvalidConfiguration	The calculation is missing, unloadable, has no stable ID, or uses the unimplemented fail-closed base class.	Repair/implement the asset and rerun Data Validation and Project Health.
RecursiveEvaluation	Calculation code started another custom magnitude evaluation before returning.	Keep calculations side-effect-free; defer gameplay operations until the outer transaction completes.
NonFiniteMagnitude	The input, configured math, or returned magnitude is NaN or infinite.	Sanitize inputs and guard division/overflow before returning Success.

EMFAttributeSnapshotResult

Used when capturing or atomically restoring attribute snapshots.

Value	Cause or meaning	Recommended response
Success	Capture or restore completed atomically.	Persist the snapshot or continue from the applied values.
InvalidWorld	No live attribute subsystem was available.	Perform save/load against the correct active game world.
InvalidEntity	The target handle is unset or stale.	Reacquire the entity before capture or restore.
MassIsProcessing	Direct snapshot access would overlap Mass processing.	Capture on a safe lifecycle tick; for restore, use Queue Mass Forge Attribute Snapshot Restore.
MissingSchema	A required domain schema is not configured.	Restore the schema configuration before handling snapshots.
MissingFragment	The entity lacks a fragment required by a snapshot attribute.	Use a compatible Entity Config or migrate into an appropriate archetype.
EmptySnapshot	The snapshot contains no values.	Treat it as absent save data or populate it through a successful capture.
UnsupportedVersion	FormatVersion is not supported by this plugin build.	Compare SnapshotFormatVersion with ExpectedFormatVersion; upgrade through a supported plugin path or reject the save with a user-facing message.
SchemaVersionMismatch	The project schema generation differs from the snapshot.	Compare SnapshotSchemaVersion with ExpectedSchemaVersion, then apply each required migration asset in order before restore.
DuplicateAttribute	The snapshot contains the same stable attribute ID more than once.	Repair the producer or migration; never choose one duplicate implicitly.
UnknownAttribute	A saved stable ID is not present in current schemas.	Add an explicit rename/remove migration rule.
InvalidValue	A saved value is NaN or infinite.	Reject or repair the corrupted save; do not inject the value into Mass state.
QueueFull	The bounded deferred snapshot-restore queue has no pending capacity.	Defer or shed the load; raise Max Pending Queued Snapshot Restores only after measuring copied-payload memory and frame cost.

EMFAttributeSnapshotMigrationResultCode

Returned by one explicit snapshot migration step.

Value	Cause or meaning	Recommended response
Success	The migration produced a complete target-version snapshot.	Continue the migration chain or restore the final snapshot.
InvalidMigration	The migration asset is null or fails its own validation.	Correct its ID, adjacent versions, rules, and duplicate mappings.
UnsupportedSnapshotFormat	The input binary format is not understood.	Load it with a compatible plugin version or provide an external format converter.
SourceVersionMismatch	The input schema version does not equal the migration's source version.	Select the next adjacent migration in the chain.
EmptySnapshot	The migration input has no attribute values.	Treat the save as missing/corrupt or start from a valid captured snapshot.
InvalidAttribute	A source or rename target ID in the snapshot/rules is invalid.	Repair the stable IDs and validate the migration asset.
InvalidValue	An input value is NaN or infinite.	Reject or repair the corrupted save before migration.
DuplicateAttribute	Migration would produce duplicate target identities.	Remove conflicting rules or resolve converging renames explicitly.

EMFEntityStateSnapshotResult

Used when capturing, validating, directly restoring, or queuing the versioned durable entity-state snapshot.

Value	Cause or meaning	Recommended response
Success	Capture, validation, or restore completed atomically.	Persist the snapshot or continue from the fully restored state.
InvalidWorld	No live Mass Forge world or required subsystem was available.	Use a live object from the intended gameplay world and avoid world teardown.
InvalidEntity	The entity handle is unset, stale, or belongs to another world.	Reacquire the complete entity index/serial before capture or restore.
MassIsProcessing	A direct operation would read or mutate fragments during Mass processing.	Capture at a safe lifecycle point or use Queue Mass Forge Entity State Restore for restore.
UnsupportedVersion	The snapshot format is not understood by this plugin build.	Load it with a compatible plugin or migrate it through an explicitly supported format path.
SchemaVersionMismatch	The nested attribute schema generation differs from the project schema.	Apply the required ordered attribute migrations before restoring the complete snapshot.
InvalidAttributeSnapshot	The nested attribute payload failed format, schema, identity, value, capacity, or fragment validation.	Inspect AttributeResult, repair or migrate the entire payload, and retry without partial application.
MissingGameplayTagFragment	The snapshot includes counted tags but the target archetype has no tag fragment.	Use a compatible Entity Config with the Gameplay Tag Trait.
InvalidGameplayTag	A saved Gameplay Tag is empty or not registered.	Repair the save producer or restore the required project tag registration.
InvalidGameplayTagCount	A saved exact tag count is outside the supported positive compact range.	Reject or repair the corrupted count before restore.
DuplicateGameplayTag	The same exact Gameplay Tag occurs more than once.	Merge it into one exact count; do not choose a duplicate implicitly.
GameplayTagCapacityExceeded	Saved exact tags exceed the fixed fragment capacity.	Migrate to a compatible bounded payload or redesign the target state budget.
MissingAbilityFragment	The snapshot includes ability state but the target archetype has no ability fragment.	Use a compatible Entity Config with the Ability Trait.
InvalidAbilityId	An ability grant has an empty stable ID or ability data appears while abilities are excluded.	Repair the snapshot producer and resolve every grant through a current stable ability ID.
DuplicateAbilityId	The same stable Ability ID occurs more than once.	Keep one authoritative grant record per ability.
AbilityCapacityExceeded	Saved grants exceed the target's fixed ability capacity.	Migrate or trim deliberately before restore; never accept an implicit partial grant list.
InvalidAbilityTime	An individual cooldown remaining value is negative, NaN, or infinite.	Reject or repair the save and persist remaining gameplay seconds only.
InvalidChargeState	Stored charge recovery has an invalid time or inconsistent scheduled flag.	Repair the charge record so unscheduled recovery is zero and every time is finite/non-negative.
InvalidCooldownGroup	A shared/global cooldown has an empty ID or non-positive/non-finite remaining time.	Remove expired groups and repair the remaining duration or stable group identity.
DuplicateCooldownGroup	The same shared/global cooldown ID occurs more than once.	Merge it into one authoritative remaining duration.
CooldownGroupCapacityExceeded	Saved active groups exceed the target's fixed group capacity.	Migrate to a compatible bounded payload; do not partially restore groups.
ActiveAbilityLifecycle	A format-1/2/3 restore targeted an entity with an active cast/channel that the legacy payload cannot describe.	Reach an idle ability boundary or restore a compatible format-4 snapshot; legacy restore never erases the lifecycle implicitly.
ActivePersistentEffects	A format-1/2 restore targeted an entity with active Persistent Effects that the legacy payload cannot describe.	End those effects deliberately or restore a compatible format-3 snapshot; legacy restore never erases them implicitly.
TransactionInProgress	A re-entrant direct restore was requested while another entity-state restore was publishing its transaction.	Defer the new operation through the bounded queue and handle its terminal completion.
QueueFull	The bounded entity-state restore queue has no pending capacity.	Throttle or defer the producer; raise Max Pending Queued Entity State Restores only after profiling memory and frame cost.
InvalidRegenerationState	Regeneration timing contains an invalid/duplicate target, non-finite or out-of-range remainder, changed schema identity, excess rules, or format-1-only forbidden fields.	Reject or explicitly migrate the payload; keep continuous-rule remainder at zero and interval remainder below its tick interval.
MissingRegenerationFragment	A format-2-or-newer snapshot includes regeneration timing but the destination archetype has no regeneration fragment.	Restore into a compatible Entity Config with the Regeneration Trait.
RegenerationProfileMismatch	The destination's unique regeneration target set or tick intervals differ from the format-2-or-newer snapshot.	Use the matching profile or explicitly migrate/reset timing before restore; Mass Forge will not remap a phase by array position.
InvalidPersistentEffectState	A format-3-or-newer effect section has inconsistent duration/period/backlog state, invalid portable context/tags/modifiers, missing reversible bases, or effective attributes that do not match those bases and contributions.	Reject or explicitly migrate the save; do not patch runtime fragment slots or accept partial effect ownership.
MissingPersistentAttributeModifierFragment	The destination or captured active-effect archetype lacks the companion fragment required for reversible contributions.	Use the Persistent Effects Trait on a compatible Entity Config and repair any custom archetype construction.
MissingPersistentEffectDefinition	A saved persistent or periodic soft asset reference is absent or cannot be loaded.	Restore the referenced asset at its stable path or explicitly migrate/remove that saved effect before restore.
PersistentEffectDefinitionMismatch	A loaded persistent or periodic asset's stable Effect ID differs from the ID guarded by the save.	Restore the identity-compatible asset or run an explicit project SaveGame migration; never reinterpret it silently.
PersistentEffectCapacityExceeded	The save exceeds 16 active effects or 24 reversibly modified attributes.	Migrate or reduce the payload deliberately; Mass Forge refuses partial restoration.
InvalidAbilityLifecycleState	The format-4 lifecycle section has inconsistent include flags, grants, phase, timing, commit state, pulse count/backlog, target mode, or forbidden legacy-format data.	Reject or explicitly migrate the complete save; never infer missing lifecycle state or patch the payload partially.
MissingAbilityLifecycleDefinition	The saved active lifecycle's soft Ability reference is empty, missing, or cannot be loaded.	Restore the referenced Ability asset at its stable path or explicitly migrate/remove that lifecycle before restore.
AbilityLifecycleDefinitionMismatch	The loaded Ability differs from the saved stable ID, Save Compatibility Version, execution type, cast time, channel duration, or channel period.	Restore a behavior-compatible asset or run an explicit project SaveGame migration; do not continue old timing under changed authoring.
MissingAbilityLifecycleTargetBinding	An externally targeted lifecycle was captured without a stable relationship key or restored without its runtime target binding.	Store a project-owned stable target key during capture, recreate the target, and supply the matching key plus new entity handle during restore.
AbilityLifecycleTargetReferenceMismatch	The supplied runtime target binding's project-owned key does not equal the key saved with the lifecycle.	Resolve the exact saved relationship and resubmit with the identical key; do not guess by Actor, position, or array order.
InvalidAbilityLifecycleTarget	The external target binding is unset, stale, not a live full-generation entity, or collapses the external relationship onto the restored source.	Recreate and resolve the intended distinct target entity, then retry with its current handle.

EMFEntityStateLifecycleTargetMode

Describes the portable target relationship stored for one format-4 active Ability Lifecycle.

Value	Cause or meaning	Recommended response
None	The active cast/channel has no target and stores no target reference.	Use the ordinary capture and restore nodes; do not invent a binding.
Self	The active cast/channel targeted the saved entity itself.	Use the ordinary restore path; Mass Forge rebinds it to the restored destination entity.
External	The active cast/channel targeted another entity, represented only by a project-owned stable relationship key in the save.	Recreate the target and supply the matching key plus its current full-generation handle to the lifecycle-target restore variant.

EMFGameplayTagResult

Used by counted tag mutations and queries.

Value	Cause or meaning	Recommended response
Success	The tag operation or query completed.	Use the exact count and hierarchical-match fields as appropriate.
InvalidWorld	No live Gameplay Tag subsystem was available.	Supply a valid world context.
InvalidEntity	The entity handle is unset or stale.	Reacquire the entity handle.
MissingFragment	The entity lacks the Mass Forge Gameplay Tag fragment.	Add the Gameplay Tag Trait to its Entity Config.
InvalidTag	The Gameplay Tag is empty or not registered.	Select a registered project tag.
InvalidCount	The requested add/remove count is outside the supported positive range.	Pass a positive bounded count.
TagNotFound	A remove/query expected an exact owned tag that is absent.	Treat absence as gameplay state or correct the requested tag.
InsufficientCount	Removal exceeds the exact owned count.	Clamp the request deliberately or correct the producer.
CountOverflow	Adding would exceed the compact counter's supported maximum.	Reduce stacking or redesign the counter semantics.
NoFreeTagSlot	The entity's bounded tag fragment is full.	Remove unused tags or redesign the archetype/state budget.
MassIsProcessing	Direct tag access would overlap Mass processing.	Use the queued Add/Remove node for one raw count change, or a queued Instant Effect for an atomic multi-change transaction.
QueueFull	The bounded counted-tag queue has no pending capacity.	Defer or shed the burst; tune queue limits only after profiling.
InvalidOperation	Native code supplied an out-of-range tag-operation enum value.	Pass only Add or Remove; treat other values as corrupted input.

EMFEffectDispatchResult

Returned by Entity/Actor cross-ownership Instant Effect dispatch.

Value	Cause or meaning	Recommended response
Success	Exactly one supported target route accepted the effect.	Inspect Route, resolved endpoints, and the nested application result.
InvalidWorld	No live world/subsystem could be resolved.	Pass a context object from the intended game world.
InvalidSource	The explicit source Actor/entity is invalid or cross-world.	Correct or omit the optional source as the node contract allows.
InvalidTarget	The target Actor/entity is null, stale, or cross-world.	Reacquire a live target.
InvalidEffect	The Instant Effect asset is null or invalid.	Repair the effect asset and validate its dependencies.
UnsupportedTarget	The Actor is neither Mass-represented nor an effect receiver.	Add the receiver interface/component or use a supported Mass entity target.
MultipleReceivers	More than one receiver component would make routing ambiguous.	Keep exactly one receiver component or implement the Actor interface directly.
EntityApplicationFailed	The Mass route was selected but its atomic effect transaction failed.	Inspect EntityResult and EntityApplication for the precise failure.
ReceiverRejected	The selected ordinary-Actor receiver declined the effect.	Inspect project receiver logic; retry only when its rejection condition changes.

EMFPersistentEffectResult

Used by persistent-effect application, removal, query, stacking, and periodic execution.

Value	Cause or meaning	Recommended response
Success	The requested persistent-effect operation completed.	Use the handle, stack disposition, and timing data returned.
InvalidWorld	No live persistent-effect subsystem was available.	Supply a valid world context.
InvalidEntity	The target handle is unset or stale.	Reacquire the entity.
MassIsProcessing	Direct fragment access would overlap Mass processing.	Schedule the operation from a safe phase.
InvalidEffect	The Persistent Effect asset is null or fails validation.	Repair its ID, duration, stacking, modifiers, tags, and dependencies.
MissingFragment	The entity lacks persistent-effect instance storage.	Add the Persistent Effects Trait.
MissingAttributeModifierFragment	Reversible attribute modifiers require storage absent from the archetype.	Enable persistent attribute modifiers in the Entity Config.
MissingAttributeFragment	An authored modifier or pulse targets a missing attribute domain fragment.	Add the Attributes Trait/domain or change the effect.
MissingAttributeSchema	A required attribute domain schema is not configured.	Configure the schema in project settings.
UnknownAttribute	An authored stable attribute ID no longer resolves.	Repair the asset or migrate the attribute identity.
MissingMagnitudeParameter	A context-backed magnitude lacks its named scalar.	Supply the parameter or correct the effect asset.
InvalidModifierMagnitude	A resolved persistent modifier is NaN or infinite.	Correct authored values, context inputs, or custom calculations.
AttributeCaptureFailed	Snapshot-at-application could not read a required source/target attribute.	Inspect the failed binding, fragments, entity, and processing phase.
AttributeCaptureCapacityExceeded	The effect needs more captured values than its bounded instance storage permits.	Reduce unique captures or split the effect.
ModifierCapacityExceeded	Applying the effect would overflow bounded persistent modifier storage.	Remove/split modifiers or budget more storage in a future archetype design.
NoFreeEffectSlot	The entity has no free persistent-effect instance slot.	Remove/expire effects or reduce simultaneous effect variety.
InvalidHandle	A remove/query handle is unset, malformed, or for another entity.	Retain the exact returned handle and validate ownership before use.
NotFound	The handle was once plausible but no active instance matches it.	Treat it as already removed/expired and discard the handle.
InitialApplicationFailed	The authored apply-on-start periodic/instant payload failed atomically.	Inspect the nested Instant Effect inputs and target configuration.
StackLimitReached	The selected stacking rule cannot add another stack.	Treat this as expected gameplay or choose a refresh/replace policy.
StrongerOrEqualEffectActive	Strongest-wins rejected a weaker or equal incoming effect.	Keep the current effect or submit a genuinely stronger value.
StackOperationInProgress	Re-entrant listener code attempted to alter the same stack transaction.	Defer the nested operation and avoid recursive mutation.
IncompatibleStack	An existing stable stack identity has incompatible authored/runtime structure.	Keep stack definitions structurally consistent and use a new ID for a different contract.
MissingGameplayTagFragment	Effect tag gates/grants require tag storage absent from the entity.	Add the Gameplay Tag Trait.
MissingRequiredTag	The target lacks an authored prerequisite tag.	Treat as a gameplay gate or grant the prerequisite first.
BlockedByTag	The target owns an authored immunity/blocking tag.	Respect the immunity or remove it through an explicit cleanse/dispel flow.
GameplayTagFailure	Lifecycle tag validation or atomic tag mutation failed.	Inspect tag validity, counts, capacity, and the entity's tag fragment.
QueueFull	The bounded persistent Apply/Remove queue has no pending capacity.	Defer or shed the burst; tune limits only after measuring queue pressure.
MagnitudeCalculationFailed	A persistent attribute contribution's custom calculation failed before the instance committed.	Inspect the failed modifier and nested calculation response; the effect and all lifecycle changes remain unapplied.

EMFPersistentEffectStackDisposition

Describes what a successful persistent-effect application did to stack state.

Value	Cause or meaning	Recommended response
AddedNewInstance	A new independent or first stack instance was created.	Track the returned handle when later removal/query is needed.
RefreshedExisting	Existing duration/timing was refreshed without creating a new instance.	Refresh presentation timing for the existing handle.
ExtendedExisting	Existing duration was increased by the stacking rule.	Update duration UI from the returned live state.
ReplacedExisting	The previous compatible instance was removed and replaced.	Stop old presentation and bind to the returned replacement handle.
ReplacedWithStronger	Strongest-wins accepted the incoming stronger instance.	Present the upgraded magnitude and replacement lifecycle.

EMFPersistentEffectRemovalReason

Published when a persistent effect leaves active state.

Value	Cause or meaning	Recommended response
Manual	A caller explicitly removed or dispelled the instance.	End presentation normally and record the manual source if needed.
Expired	Finite duration reached zero.	End duration UI/VFX and release the handle.
Replaced	A stacking rule replaced the instance.	Transition presentation to the replacement instance.
EntityInvalidated	The owning entity was destroyed or became invalid.	Drop all project-side references without targeting the old handle.
Cancelled	A classification cleanse/cancel or lifecycle rollback removed it.	Use project context/events to explain the cancellation when relevant.

EMFDamageResult

Used by immediate damage applications, queued receipts, and queued completions.

Value	Cause or meaning	Recommended response
Success	Damage calculated and committed atomically.	Use the complete calculation, shield/health, critical, death, and context fields.
InvalidWorld	No live damage subsystem was available.	Supply a valid world context.
MassIsProcessing	Immediate damage would overlap Mass processing.	Use Queue Mass Forge Damage.
InvalidDefinition	The Damage Definition is null or fails validation.	Repair it in the authoring overview and rerun Project Health.
InvalidSource	A required source entity/Actor is invalid.	Reacquire the source or use an environmental/Actor request allowed by the definition.
InvalidTarget	The target entity is unset, stale, or lacks required state.	Reacquire a valid damageable target.
SelfDamageDisallowed	Source and target match while the definition forbids self damage.	Choose another target or explicitly enable self damage.
TargetAlreadyDead	The target already satisfies the configured death condition.	Suppress repeat hits/rewards and wait for lifecycle handling.
MissingRequiredTag	The target lacks a tag required by the definition.	Treat as a gate or establish the prerequisite tag first.
BlockedByTag	An authored immunity/blocking tag is present.	Respect or explicitly remove the immunity.
BlockedByPolicy	A project damage-policy provider vetoed the request.	Inspect BlockingPolicyId and BlockingPolicyReason.
PolicyEvaluationInProgress	A provider re-entered damage while policies were already being evaluated.	Defer nested damage and keep providers side-effect-free.
GameplayTagFailure	Required/death tag work failed validation or atomic commit.	Inspect GameplayTagResult, failed tag, trait, counts, and capacity.
AttributeReadFailed	A configured formula attribute could not be read.	Inspect AttributeResult and FailedAttribute; repair schema/archetype setup.
InvalidMagnitude	Base damage or a resolved calculation became NaN, infinite, or invalid.	Sanitize inputs and definition values before applying damage.
TransactionFailed	The final atomic Health/Shield/death-tag effect failed.	Inspect the nested transaction result and failed operation.
QueueFull	The bounded pending-damage queue is full.	Throttle damage producers or raise the measured queue budget.

EMFDamagePolicyDecision

Each policy provider returns one decision; any Deny vetoes the damage request.

Value	Cause or meaning	Recommended response
Abstain	This provider has no opinion for the request.	Continue evaluating later providers.
Allow	This provider permits the request but does not override another provider's veto.	Continue evaluation; use it for diagnostics if desired.
Deny	This provider blocks the request.	Supply stable policy/reason IDs and present the relevant gameplay feedback.

EMFDamagePolicyProviderResult

Returned by damage-policy provider registration and unregistration.

Value	Cause or meaning	Recommended response
Success	Registration/unregistration changed the live provider registry.	Continue normal lifecycle handling.
InvalidWorld	No live damage subsystem was available.	Register from a live object in the intended world.
InvalidProvider	The provider is null, destroyed, or lacks the required interface.	Pass a live implementing object/component.
WrongWorld	The provider belongs to a different world.	Register it with its own world's subsystem.
AlreadyRegistered	The same live provider is already present.	Treat setup as idempotent; do not add another registration.
CapacityReached	The bounded world provider registry is full.	Consolidate policy rules or remove unused providers.
EvaluationInProgress	Registry mutation was attempted during a policy callback.	Defer registration changes until evaluation completes.
NotRegistered	Unregistration found no matching live provider.	Treat it as already removed or correct the lifecycle pairing.

EMFDeathHandlingRequestResult

Describes the immediate post-death lifecycle request attached to successful killing damage.

Value	Cause or meaning	Recommended response
NotRequested	The target survived or the definition keeps dead entities.	Apply project lifecycle behavior only if separately configured.
ProjectDeactivationRequested	Mass Forge emitted a request for project-owned pooling/deactivation.	Handle the request ID once and report completion in project logic.
DestructionQueued	Safe deferred Mass-entity destruction was accepted.	Correlate the later destruction completion with the request ID.
QueueFull	Deferred destruction could not be scheduled.	Keep the dead entity inert, throttle deaths, and retry through controlled project logic if appropriate.

EMFDeathDestructionResult

Final result published for queued Mass-entity destruction.

Value	Cause or meaning	Recommended response
Destroyed	The generation-checked entity was still valid and was destroyed.	Release project-side presentation and references.
EntityAlreadyInvalid	The entity was already destroyed/reused before the request executed.	Treat destruction as terminal and never act on the old handle.

EMFAbilityResult

Shared by ability ownership, checks, activation, lifecycle control, AI requests, and queued operation receipts/completions.

Value	Cause or meaning	Recommended response
Success	The operation completed or an activation/lifecycle request was accepted.	Inspect the enclosing receipt/result for request ID and committed effects.
InvalidWorld	No live ability subsystem was available.	Supply a valid world context.
InvalidEntity	The source entity is unset or stale.	Reacquire the source handle.
MissingAbilityFragment	The source archetype lacks ability state.	Add the Mass Forge Ability Trait.
InvalidAbility	The Ability asset is null, invalid, or changed incompatibly.	Repair it in the authoring overview and rerun Project Health.
NotGranted	The source does not own the requested stable ability ID.	Grant it first or correct the ID.
AlreadyGranted	A grant request targeted an already-owned ability.	Treat the grant as unnecessary or revoke deliberately before replacement.
NoFreeAbilitySlot	The compact ability fragment has no free grant slot.	Revoke an ability or reduce the loadout.
QueueFull	The shared bounded Activate/Grant/Revoke/Cancel/Interrupt or AI-request capacity is exhausted.	Throttle producers or increase the measured budget.
TargetRequired	The ability requires a target but none was supplied.	Select and pass a valid target.
InvalidTarget	The supplied target is stale or otherwise invalid.	Reacquire the target.
SelfTargetNotAllowed	Source and target match while self-targeting is disabled.	Select another target or change the authored targeting rule.
TargetingPolicyRejected	A targeting policy denied the source/target pair.	Inspect the policy result/index/ID and correct range or project conditions.
TargetingPolicyEvaluationInProgress	Policy code re-entered activation during evaluation.	Keep policies side-effect-free and defer nested activation.
OnCooldown	The individual ability cooldown has not expired.	Wait for the reported remaining time.
OnCooldownGroup	A shared/global cooldown group is active.	Query the group remaining time and wait.
NoFreeCooldownGroupSlot	Starting a new named cooldown would exceed bounded group storage.	Consolidate group names or reduce simultaneous groups.
NoCharges	The ability has no available charge.	Wait for charge recovery or change the loadout rules.
CannotAfford	One or more cost attributes are below their required values.	Inspect the failed cost/attribute and restore resources.
RequirementNotMet	An authored source/target attribute comparison failed.	Inspect the requirement index, subject, observed value, and threshold.
MissingGameplayTagFragment	Ability tag gates/effects require tag storage absent from an entity.	Add the Gameplay Tag Trait to the relevant archetype.
MissingRequiredTag	A required source/target tag is absent.	Establish the prerequisite or treat this as an expected gate.
BlockedByTag	A source/target blocking tag is present.	Respect or explicitly cleanse the blocking state.
InvalidAttribute	A cost, requirement, or nested effect references an unresolved attribute.	Repair the stable attribute ID/schema dependency.
MissingMagnitudeParameter	A nested effect needs a context scalar missing from the ability defaults/context.	Add the named default/input parameter.
GameplayTagEffectFailed	A nested tag transaction failed.	Inspect failed tag details, counts, capacity, and fragment setup.
PersistentEffectFailed	A referenced persistent effect could not apply.	Inspect the nested persistent result and asset/archetype setup.
TransactionInProgress	Re-entrant code attempted a conflicting ability transaction.	Defer nested work until the current transaction/event returns.
ActiveAbilityInProgress	The source already has an active cast/channel.	Wait, cancel/interrupt it when allowed, or reject the new input.
NoActiveAbility	A lifecycle query/control request found no active cast/channel.	Treat it as already ended and clear stale presentation.
CancellationBlocked	The active ability does not permit voluntary cancellation.	Continue it or use a permitted interruption path.
InterruptionBlocked	The active ability is immune to interruption.	Respect the authored rule.
InvalidRequestId	A supplied AI request ID is non-positive or malformed.	Retain the positive ID returned by an accepted receipt.
RequestNotFound	No tracked AI request matches the ID.	Correct the ID or treat it as expired/forgotten history.
RequestNotTerminal	Forget was requested while the AI ticket is still pending/active.	Cancel or wait for a terminal state first.
RequestAlreadyTerminal	A control operation targeted a ticket that has already finished.	Read its terminal state and stop issuing control requests.
RequestCancelled	A queued AI activation was cancelled before execution.	Treat it as a terminal cancellation, not a system failure.
InvalidEffect	A referenced Instant/Persistent Effect is invalid at execution time.	Repair the dependency and rerun Project Health.
MassIsProcessing	Direct ability state access would overlap Mass processing.	Use the matching queued operation or invoke the direct operation from a safe phase.
LifecycleChanged	A queued Cancel/Interrupt captured one lifecycle ID, but a different lifecycle is now active on that source.	Treat the request as safely stale; inspect the new lifecycle and submit a new request only if it should also stop.
ConditionRejected	A project-authored activation condition returned a non-passing response.	Inspect the failed condition index, stable condition ID, result, and reason; treat expected game-rule denial separately from invalid configuration.
ConditionEvaluationInProgress	Condition code re-entered ability admission while another condition was being evaluated.	Keep conditions side-effect-free and defer nested gameplay work until the current activation completes.
MagnitudeCalculationFailed	A nested Instant Effect custom magnitude failed while the ability transaction was staged.	Inspect FailedEffectId, FailedModifierIndex, and MagnitudeCalculationResponse; costs, effects, cooldown, charges, and lifecycle state remain uncommitted.
ExecutionPlanRejected	The assigned execution plan rejected evaluation or returned invalid, unsafe, or over-limit output.	Inspect ExecutionPlanResponse, its stable plan ID/result/reason, and the plan's returned references and parameters; activation state remains uncommitted.
ExecutionPlanEvaluationInProgress	Plan code re-entered ability admission while another plan evaluation was active.	Keep execution plans deterministic and side-effect-free; defer nested gameplay operations until the current evaluation returns.

EMFAbilityExecutionPlanResult

Detailed response from an optional Blueprint/C++ Ability Execution Plan.

Value	Cause or meaning	Recommended response
Success	The plan returned a payload that may proceed to framework validation and transaction staging.	Let Mass Forge validate and commit it; do not apply the described effects manually.
Rejected	Project logic intentionally declined to produce an activation or channel-pulse payload.	Inspect the stable plan ID/reason and treat expected gameplay denial separately from setup failure.
InvalidWorld	The query lacks a live world or crosses world ownership.	Evaluate from the same active world as the source and target.
InvalidSource	The query's source entity or Actor is no longer valid.	Reacquire the source and retry only through normal ability admission.
InvalidTarget	Target output requires a valid target, or the supplied target/Actor is stale or cross-world.	Enable the Ability's target contract and pass a current target from the same world.
InvalidConfiguration	The plan is missing/unloadable/unidentified, has an invalid merge mode, or uses the unimplemented fail-closed base class.	Repair or implement the plan, assign a unique PlanId, and rerun Data Validation and Project Health.
RecursiveEvaluation	Plan code triggered another plan evaluation before returning.	Remove gameplay mutations and nested activation from the callback; return only a transaction description.
OutputLimitExceeded	The payload exceeds 64 combined effects or 64 parameter overrides.	Split the design into bounded operations or reduce the payload; do not raise hidden per-activation work.
InvalidEffect	A returned effect is missing, unloadable, unidentified, or Persistent Effect output was returned for a channel pulse.	Repair the reference/ID and keep channel payloads Instant-only.
InvalidParameter	A returned parameter has no name or a NaN/infinite value.	Supply a stable non-empty name and finite scalar.

EMFAbilityRequestOperation

Identifies which operation produced an FMFAbilityRequestCompletion.

Value	Cause or meaning	Recommended response
Activate	The request attempted an Ability activation or cast/channel admission.	Inspect Result and the nested activation diagnostics.
Grant	The request attempted to add a validated Ability definition to the entity.	On failure, inspect the entity, definition, and bounded grant capacity.
Revoke	The request attempted to remove one submitted Ability ID and its runtime state.	Treat NotGranted as an already-absent ownership state when appropriate.
Cancel	The request attempted voluntary cancellation of the exact captured lifecycle.	Handle blocked, ended, or replaced lifecycles explicitly.
Interrupt	The request attempted external interruption of the exact captured lifecycle.	Handle immunity, ended, or replaced lifecycles explicitly.

EMFAbilityTargetingPolicyResult

Detailed response from a reusable ability targeting policy.

Value	Cause or meaning	Recommended response
Allowed	The policy accepts this source/target pair.	Continue evaluating later policies.
Rejected	Custom policy logic rejected the pair.	Inspect the policy's stable reason and provide gameplay feedback.
InvalidWorld	The policy query has no valid world.	Supply a live world context.
InvalidSource	The source entity/Actor is invalid for this policy.	Reacquire or correct the source.
InvalidTarget	The target entity/Actor is invalid for this policy.	Reacquire or correct the target.
MissingSourcePosition	The selected position source cannot resolve a source location.	Add a Mass transform/representation or change the policy position mode.
MissingTargetPosition	The selected position source cannot resolve a target location.	Add a Mass transform/representation or change the policy position mode.
BelowMinimumRange	Distance is smaller than the authored minimum.	Move apart or adjust the validated minimum.
BeyondMaximumRange	Distance exceeds the authored maximum.	Move closer or adjust the validated maximum.
InvalidConfiguration	Policy settings are contradictory or non-finite.	Repair and validate the policy asset.

EMFAbilityConditionResult

Detailed response from a reusable project-authored activation condition.

Value	Cause or meaning	Recommended response
Passed	The condition allows activation to continue.	Continue evaluating later conditions.
Rejected	Project logic intentionally denied activation.	Inspect the stable condition ID and reason, then provide appropriate gameplay feedback.
InvalidWorld	The condition cannot resolve required authoritative world state.	Supply a live world or repair the condition's world-state dependency.
InvalidSource	The source entity/Actor is unusable for this condition.	Reacquire the source or handle actorless entities explicitly.
InvalidTarget	The optional/required target is unusable for this condition.	Require and reacquire a target or handle an unset target explicitly.
InvalidConfiguration	The condition asset is unimplemented or configured incorrectly.	Implement Evaluate Condition, repair the asset, and rerun validation/Project Health.

EMFAbilityTargetSelectionResult

Top-level result for built-in and provider-driven target selection.

Value	Cause or meaning	Recommended response
Success	Selection completed; an empty target array can still be a valid result.	Use bounded targets and inspect truncation/diagnostic counts.
InvalidWorld	No live Mass world could be resolved.	Supply a valid world context.
MassIsProcessing	The query cannot safely inspect Mass entity data now.	Run selection from a safe phase.
InvalidSource	A required source entity/Actor is invalid.	Reacquire or correct the source.
InvalidTarget	A collision hit did not resolve to a valid Mass target.	Treat it as a miss or resolve another target.
InvalidRequest	Radius, trace, bounds, or parameter inputs are invalid/non-finite.	Sanitize origin/end/radius/max-target inputs.
InvalidProvider	The custom provider is null, invalid, or lacks the interface.	Pass a live implementing provider.
ProviderEvaluationInProgress	Provider selection was re-entered recursively.	Keep the provider side-effect-free and defer nested selection.
ProviderFailed	The provider returned a non-success response.	Inspect ProviderId and Reason, then correct project logic or inputs.

EMFAbilityTargetProviderResult

Authored response returned by a custom target provider before Mass Forge sanitizes its handles.

Value	Cause or meaning	Recommended response
Success	The provider produced a candidate list for validation.	Return stable provider identity and let Mass Forge bound/de-duplicate it.
Rejected	Project logic intentionally declined the query.	Supply a stable reason and treat it as a controlled selection failure.
InvalidRequest	Project logic considers the supplied query malformed/unsupported.	Validate query parameters before invoking the provider.

EMFAbilityAIRequestStatus

Pollable lifecycle status for a tracked AI activation request.

Value	Cause or meaning	Recommended response
Invalid	No valid tracked state is represented.	Check the enclosing query result and request ID.
Pending	Accepted work is waiting in the bounded activation queue.	Continue polling without resubmitting.
Active	The request started a live cast/channel lifecycle.	Read lifecycle progress and continue polling.
Succeeded	Activation or lifecycle completed successfully.	Consume the terminal result and forget the ticket when no longer needed.
Failed	Activation or commit ended with a non-success result.	Inspect the nested activation/lifecycle diagnostics.
Cancelled	The request/lifecycle ended through allowed cancellation.	Treat as a terminal controlled outcome.
Interrupted	The active lifecycle was interrupted.	Treat as terminal and inspect interruption context in project events.

EMFAbilityLifecycleEndReason

Terminal reason published for a cast/channel lifecycle.

Value	Cause or meaning	Recommended response
Completed	The lifecycle reached its authored end and committed successfully.	Finish presentation and consume the activation result.
Cancelled	A permitted voluntary cancellation ended it.	Roll back/stop presentation according to project UX.
Interrupted	A permitted external interruption ended it.	Present interruption feedback and clear active state.
CommitFailed	Final or periodic atomic work could not commit.	Inspect the detailed ability/effect result and repair runtime prerequisites.
AbilityRevoked	The granted ability was removed while its lifecycle was active.	Treat the lifecycle as terminated and update loadout UI.
SourceInvalid	The source entity became invalid before completion.	Drop the lifecycle and all stale source references.

EMFHighVolumeEffectResult

Admission or terminal outcome for the per-entity compiled Apply/Remove mailbox.

Value	Cause or meaning	Recommended response
None	The mailbox has no admission or execution result.	Submit a command or wait for a completed mailbox before consuming.
Accepted	A valid command now owns the entity's single mailbox.	Wait for the high-volume processor and consume the correlated completion.
Success	Every compiled attribute/tag operation committed atomically.	Consume the completion and release the mailbox.
Busy	A pending command or unconsumed completion already owns the mailbox.	Do not overwrite or spin; consume completion before resubmitting.
InvalidRequestId	The project supplied correlation ID 0 or a negative value.	Allocate a positive per-producer correlation ID.
InvalidEffectIndex	The numeric effect index is outside the archetype's compiled table.	Resolve/cache the ID from the matching shared fragment before entity iteration.
InvalidOperation	The operation is neither Apply nor Remove.	Pass a declared EMFHighVolumeEffectOperation value.
InvalidDefinition	The selected compiled side is empty or exceeds its fixed capacity.	Repair the trait/effect assets and recreate the entity template.
MissingAttributeSlot	A compiled domain/slot cannot resolve against the entity fragments.	Verify the Attributes Trait/schema and rebuild stale templates after schema changes.
InvalidMagnitude	Existing state, the compiled magnitude, or projected arithmetic is non-finite.	Repair the source asset/state; the command changed nothing.
MissingGameplayTagFragment	The selected side changes tags but this archetype has no tag fragment.	Add/configure the Gameplay Tag Trait or remove tag operations from the pair.
GameplayTagFailure	A projected tag operation failed validation, count, or capacity rules.	Inspect GameplayTagResult and FailedOperationIndex; the command changed nothing.

EMFEntityInspectionResult

Returned by point-in-time entity inspection captures.

Value	Cause or meaning	Recommended response
Success	A bounded snapshot was captured.	Render its built-in/custom sections without treating them as simulation authority.
InvalidWorld	No live inspection subsystem was available.	Select an object/entity from the intended active world.
InvalidEntity	The requested handle or represented Actor is invalid/stale.	Reacquire the selection.
MassIsProcessing	Snapshotting would overlap Mass processing.	Refresh on a later editor/game tick.

EMFInspectionProviderResult

Returned by custom inspection-provider registration and unregistration.

Value	Cause or meaning	Recommended response
Success	The provider registry changed as requested.	Pair registration with lifecycle-safe unregistration.
InvalidWorld	No live inspection subsystem was available.	Register from a live object in the intended world.
InvalidProvider	The provider is null or no longer valid.	Pass a live object.
UnsupportedProvider	The object does not implement the inspection-provider interface.	Implement the interface or use the supplied component pattern.
AlreadyRegistered	The provider is already in the registry.	Treat setup as idempotent and avoid duplicate registration.
CapacityReached	The bounded provider registry is full.	Consolidate sections/providers or unregister unused providers.
NotRegistered	Unregistration found no matching provider.	Treat it as already removed or correct lifecycle pairing.

EMFGameplayEventHistoryResult

Returned by bounded gameplay-event history queries and entity watch-list operations.

Value	Cause or meaning	Recommended response
Success	The query or watch-list operation completed.	Consume the chronological records or continue the diagnostic session.
InvalidWorld	The gameplay-event subsystem no longer belongs to a live world.	Reacquire the subsystem from the intended active world.
InvalidEntity	A watch handle is unset, stale, or belongs to another entity generation.	Reacquire a live entity handle before adding the watch.
AlreadyWatched	The entity is already present in the bounded watch list.	Treat the watch setup as idempotent; do not add a duplicate.
NotWatched	Removal found no matching entity in the watch list.	Treat it as already removed or verify the generation-sensitive handle.
WatchCapacityReached	The watch list already contains its maximum 64 entities.	Remove unused watches or divide diagnostics into smaller sessions.
InvalidLimit	A history query requested fewer than 1 or more than 65,536 records.	Supply a positive bounded maximum within the documented range.

EMFNetworkEntityReferenceResult

Returned when translating between a world-local Mass handle and an Unreal Mass session network identity.

Value	Cause or meaning	Recommended response
Success	The entity and session reference resolved to one current full generation.	Use the reference only within this replicated world/session.
InvalidWorld	The world or Mass entity subsystem is unavailable.	Reacquire the subsystem from the live network world.
InvalidEntity	The supplied Mass handle is unset or stale.	Reacquire the complete current entity generation.
MissingNetworkIdentity	The entity has no valid Unreal Mass network-ID fragment.	Add/configure the Mass Replication trait and wait for identity initialization.
InvalidNetworkReference	The incoming session reference is zero, negative, or larger than the native unsigned 32-bit Mass network-ID range.	Send a valid replicated network identity, never an entity index or an unchecked Blueprint integer.
UnknownNetworkReference	No authoritative registration or client bubble mapping currently owns the ID.	Wait for relevance/registration or discard a reference from another session.
StaleNetworkReference	The cached mapping no longer matches a live entity with the same ID.	Discard the mapping and reacquire current replicated state.

EMFNetworkEntityRegistryResult

Returned by the authority-side constant-time network identity registry.

Value	Cause or meaning	Recommended response
Success	The authority registry changed as requested.	Pair registration with entity retirement/unregistration.
InvalidWorld	No live network world is available.	Register through the intended world's authority subsystem.
NotServerAuthority	Registration was attempted on a remote client.	Register only where the authoritative Mass entity exists.
InvalidEntity	The supplied handle is unset or stale.	Reacquire the server's current entity generation.
MissingNetworkIdentity	The entity has no initialized Mass network ID.	Configure Mass Replication before registering gameplay identity.
DuplicateNetworkIdentity	The ID already maps to a different live entity.	Repair entity creation/identity assignment; never overwrite the earlier mapping.
AlreadyRegistered	The same ID already maps to the same full entity generation.	Treat setup as idempotent.
NotRegistered	Unregistration found no entry for that entity generation.	Treat it as already retired or repair lifecycle pairing.

EMFNetworkDefinitionRegistryResult

Returned by the authority-owned catalog of definitions approved for future network dispatch. Client input never loads assets into this catalog.

Value	Cause or meaning	Recommended response
Success	The catalog operation completed.	Continue with the returned kind/ID or resolved server object.
InvalidWorld	No live network world is available.	Register during authoritative world or match setup.
NotServerAuthority	A remote client attempted to maintain or resolve the trusted catalog.	Perform catalog work only on server authority.
InvalidDefinition	The supplied Primary Data Asset is null, destroyed, or otherwise invalid.	Retain and pass a live server-owned definition.
UnsupportedDefinitionType	The asset is not a Mass Forge Ability, Instant Effect, Persistent Effect, or Damage Definition.	Register only an explicitly supported gameplay definition family.
MissingDefinitionId	The definition or lookup has no stable authored ID.	Assign and validate the asset's stable ID before match setup.
DuplicateDefinitionId	Another object already owns that ID within the same definition family.	Rename or remove the conflicting server definition; never replace it implicitly.
AlreadyRegistered	The same object already owns that family/ID entry.	Treat repeated setup as idempotent.
NotRegistered	Explicit unregistration found no entry for that object.	Treat it as already released or repair setup/teardown pairing.
UnknownDefinition	The requested family/ID was never admitted by the server.	Reject the client request or explicitly register the preloaded asset during setup.
StaleDefinition	A registered object became invalid or its authored ID changed after admission; the stale entry was removed.	Restore immutable runtime definitions and explicitly register the corrected object again.

EMFNetworkRequestResult

Returned by server-side validation of an untrusted client request descriptor. Success authorizes later dispatch but is not a gameplay receipt.

Value	Cause or meaning	Recommended response
Success	Identity validation passed and at least one project policy allowed the request without a veto.	Dispatch through the operation's bounded authoritative queue and correlate its separate receipt.
InvalidWorld	The authority subsystem has no live world.	Reacquire it from the current server world.
NotServerAuthority	A remote client attempted to evaluate authority policy.	Send through an owner-bound server RPC adapter instead of evaluating locally.
InvalidRequestId	The client-local correlation ID is zero or negative.	Allocate a positive client-local ID before submission.
InvalidOperation	The operation is unset, structurally incomplete, has a non-finite magnitude, or has a negative count.	Build a valid operation-specific descriptor before transport.
InvalidRequester	The requester Player Controller is null/destroyed.	Invoke from the owning live connection.
WrongRequesterWorld	The requester belongs to a different world.	Reject cross-world input and reacquire the correct connection.
InvalidSourceReference	The request supplied no source network identity.	Send the authoritative source entity's session reference.
InvalidTargetReference	Damage or Persistent Effect Remove omitted its required target.	Supply the intended target's current session reference.
SourceEntityUnavailable	The source reference is unknown or stale on authority.	Stop retrying stale IDs; wait for current ownership/relevance state.
TargetEntityUnavailable	The optional/required target reference is unknown or stale.	Reacquire the target or reject the action in UI.
NoAllowingPolicy	No live project policy explicitly allowed the request.	Install/repair a bounded ownership policy; do not change the default to implicit allow.
DeniedByPolicy	A project policy vetoed the request.	Use the deciding policy ID/reason for diagnostics and do not dispatch.
InvalidPolicyResponse	A non-Abstain response omitted its stable policy ID or returned an unknown decision.	Repair the provider implementation; the request changed nothing.
EvaluationInProgress	A policy recursively evaluated or changed the registry during evaluation.	Remove policy re-entry and defer follow-up work until evaluation returns.

EMFNetworkStateResult

Returned when maintaining or immediately refreshing one Player Controller's owner-only gameplay-state relevance set.

Value	Cause or meaning	Recommended response
Success	Relevance changed or the requested capture completed without truncation.	Consume the initial/current state or wait for later semantic update events.
InvalidWorld	The component or required world subsystem has no live world.	Reacquire the owning Player Controller and component from the active network world.
InvalidOwner	The component is not the sole Mass Forge state component on a live Player Controller.	Install exactly one state component as a default Player Controller component.
NotServerAuthority	A client attempted to add, remove, clear, or force authority relevance.	Make relevance decisions on the server; clients only query replicated state.
InvalidEntity	The authoritative Mass handle is unset, stale, or was invalidated during refresh.	Reacquire the current generation or allow automatic relevance removal to complete.
MissingNetworkIdentity	The entity does not yet carry an initialized Mass network ID.	Configure Mass Replication and add relevance only after identity initialization.
AlreadyRelevant	The same session identity is already in this connection's relevance set.	Treat setup as idempotent and query its existing state.
NotRelevant	Removal or forced refresh found no matching session identity.	Treat removal as already complete or add the entity on authority first.
CapacityReached	This connection reached its configured relevant-entity bound.	Remove stale interest entries or raise the profiled bound deliberately.
CaptureDeferred	Mass was processing, so relevance was retained without reading unstable fragments.	Wait for the bounded scheduled retry and its Added/Updated event.
CaptureFailed	Registry setup, a section result combination, or a fixed payload capacity prevented a complete baseline.	Inspect entity traits/capacities and correct setup; Mass Forge never sends a truncated state.
StaleNetworkIdentity	A relevant entity's Mass network ID changed after its connection binding was created.	Retire the stale relevance entry and register/add the entity under its current immutable session identity.
InvalidAttributeRule	An attribute rule has an unset ID, a negative/non-finite step, a duplicate Attribute ID, or the rule array exceeds the fixed attribute capacity.	Correct the complete rule set and configure it again; the previous runtime policy remains unchanged.

EMFNetworkRequestPolicyProviderResult

Returned when maintaining the bounded weak server request-policy chain.

Value	Cause or meaning	Recommended response
Success	The policy registry changed as requested.	Keep lifecycle-safe registration/unregistration pairing.
InvalidWorld	No live authority world exists.	Register from a world-owned server object.
NotServerAuthority	A remote client attempted to own server request policy.	Install the provider on Game State or another authority-owned object.
InvalidProvider	The object is null or does not implement the policy interface.	Pass a live IMF_NetworkRequestPolicy object/component.
WrongWorld	The provider belongs to another world.	Register with its own world's subsystem.
AlreadyRegistered	The provider is already present.	Treat setup as idempotent.
NotRegistered	Unregistration found no matching live provider.	Treat it as already removed or correct teardown pairing.
CapacityReached	Sixteen live providers are already registered.	Consolidate related project checks or unregister unused providers.
EvaluationInProgress	Registration changed while a request policy chain was executing.	Defer registry mutation until the evaluation has returned.

EMFNetworkClientSubmissionResult

Returned immediately on the owning machine when handing a descriptor to the Player Controller request component. Submitted means only that the unreliable RPC was emitted or processed locally; wait for the server receipt before treating the request as accepted.

Value	Cause or meaning	Recommended response
Submitted	The owner-bound component assigned a positive correlation ID and handed the request to transport.	Store the ID and correlate the later server receipt and, if accepted, completion.
InvalidWorld	The component has no live world.	Submit only after the owning Player Controller and component have entered a world.
InvalidOwner	The component is not owned by a live Player Controller.	Add it as a default component of the project Player Controller class.
NotLocallyControlled	Code tried to submit through another connection's controller.	Submit only through the local owning Player Controller.
RequestIdExhausted	The component exhausted its positive signed 64-bit client request sequence.	Recreate the connection/component; never wrap or reuse correlation IDs.

EMFNetworkTransportResult

Returned by the server receipt after owner, payload, replay, rate, outstanding-capacity, policy, catalog, and backend-queue admission checks.

Value	Cause or meaning	Recommended response
Accepted	The request entered the matching bounded authoritative gameplay queue and has a positive backend ID.	Wait for the correlated terminal completion; activation completion may mean a cast/channel lifecycle started, not ended.
InvalidOwner	The replicated component is not owned by a live Player Controller.	Install the component on the Player Controller class and do not reparent it at runtime.
NotServerAuthority	Processing occurred outside authoritative server context.	Repair component replication/ownership and submit through its generated Server RPC.
InvalidPayload	Operation fields, bounds, scalar count, identities, or finite-number requirements failed.	Rebuild the operation-specific descriptor; the project policy and gameplay queues were not called.
ReplayOrOutOfOrder	The client ID was not greater than the last structurally valid ID received on this connection.	Allocate IDs monotonically through Submit Network Request; never retry with an old ID.
RateLimited	The connection exceeded its server-owned real-time request-window limit.	Back off and configure an intentional per-game limit on the component class defaults.
TooManyOutstanding	Too many accepted requests still await backend terminal events for this connection.	Wait for completion; investigate stalled world processing if capacity does not recover.
AuthorizationRejected	The authority subsystem or project policy chain rejected the request.	Inspect AuthorizationResult, PolicyId, and Reason; never bypass the deny-by-default policy.
DefinitionRejected	The stable ID did not resolve through the expected server-approved definition family.	Preload/register the correct definition on authority; never load using the client name.
BackendUnavailable	The required Mass Forge world subsystem was unavailable.	Verify plugin/world initialization and the operation's subsystem dependency.
BackendRejected	The matching bounded gameplay queue rejected admission or returned no valid backend ID.	Inspect the operation-specific result on the receipt, correct the request, or wait for queue capacity.
UnsupportedOperation	The common transport intentionally does not carry this operation, currently Entity State Restore.	Keep save restoration on a trusted project-owned server path until a separately bounded snapshot channel is implemented.

Reading compound results

• Attribute changes: branch on FMFAttributeChangeResult.Result, then use previous/new value and clamp state only on success.
• Instant Effects: read the top-level attribute result first, then failed-operation/tag fields; successful operation arrays describe the atomic commit.
• Damage: read FMFDamageApplicationResult.Result first. On layered failures, inspect AttributeResult, GameplayTagResult, FailedAttribute, FailedTag, policy identity/reason, and the nested transaction.
• Abilities: read FMFAbilityActivationResult.Result first, then requirement, targeting-policy, cost, gameplay-tag, Instant Effect, and Persistent Effect details relevant to that code.
• Queues: acceptance means Success plus a positive request ID. Rejection returns ID 0 and no completion. The later completion event is authoritative for execution-time success because complete entity generations and submitted definition identities are revalidated. See the deferred recovery matrix.
• Actor dispatch: FMFEffectDispatchReceipt.Route identifies whether Mass, an Actor interface, or a receiver component was selected; never assume an Actor uses only one ownership path.
• Projectiles: branch first on FMFProjectileLaunchReceipt.Result; after acceptance, use FMFProjectileResolveResult.Reason, then inspect the optional nested Damage result before treating impact as applied damage.