# Errors reference catalog

Every exception the framework raises has a dedicated reference page. The error message in the runtime ends with a `More:` link to its page; you should rarely need to visit this catalog directly.

If you arrived here from an error message, follow the link the message printed. If you're browsing — start with [ReplayDivergenceError](https://docs.activegraph.ai/reference/errors/replay-divergence-error/index.md) (the voice reference for the catalog) or [UnsupportedPatternError](https://docs.activegraph.ai/reference/errors/unsupported-pattern-error/index.md) (the authoring guide for pattern subscriptions).

The hierarchy itself is documented at [Concepts: Failure model](https://docs.activegraph.ai/concepts/failure-model/index.md). The event payload reason-code vocabulary is documented at [Reference: Reason codes](https://docs.activegraph.ai/reference/reason-codes/index.md).

## By category

The seven category bases match the [`ActiveGraphError` hierarchy](https://docs.activegraph.ai/reference/api/errors/index.md):

### ReplayError

- [ReplayDivergenceError](https://docs.activegraph.ai/reference/errors/replay-divergence-error/index.md)

### PatternError

- [UnsupportedPatternError](https://docs.activegraph.ai/reference/errors/unsupported-pattern-error/index.md)
- [InvalidActivateAfter](https://docs.activegraph.ai/reference/errors/invalid-activate-after/index.md)

### StorageError

- [CorruptedEventPayloadError](https://docs.activegraph.ai/reference/errors/corrupted-event-payload-error/index.md)
- [DuplicateEventError](https://docs.activegraph.ai/reference/errors/duplicate-event-error/index.md)
- [EventNotFoundError](https://docs.activegraph.ai/reference/errors/event-not-found-error/index.md)
- [InvalidStoreURL](https://docs.activegraph.ai/reference/errors/invalid-store-url-error/index.md)
- [NonSerializableEventError](https://docs.activegraph.ai/reference/errors/non-serializable-event-error/index.md)
- [SchemaVersionMismatch](https://docs.activegraph.ai/reference/errors/schema-version-mismatch/index.md)

### ExecutionError

- [LLMBehaviorError](https://docs.activegraph.ai/reference/errors/llm-behavior-error/index.md)
- [ToolError](https://docs.activegraph.ai/reference/errors/tool-error/index.md)
- [UnknownToolError](https://docs.activegraph.ai/reference/errors/unknown-tool-error/index.md)
- [ApprovalNotFoundError](https://docs.activegraph.ai/reference/errors/approval-not-found-error/index.md)
- [ReservedFieldError](https://docs.activegraph.ai/reference/errors/reserved-field-error/index.md)

### ConfigurationError

- [MissingProviderError](https://docs.activegraph.ai/reference/errors/missing-provider-error/index.md)
- [MissingToolError](https://docs.activegraph.ai/reference/errors/missing-tool-error/index.md)
- [MissingOptionalDependency](https://docs.activegraph.ai/reference/errors/missing-optional-dependency/index.md)
- [InvalidToolRegistration](https://docs.activegraph.ai/reference/errors/invalid-tool-registration/index.md)
- [InvalidRuntimeConfiguration](https://docs.activegraph.ai/reference/errors/invalid-runtime-configuration/index.md)
- [InvalidArgumentType](https://docs.activegraph.ai/reference/errors/invalid-argument-type/index.md)
- [RuntimeContextRequiredError](https://docs.activegraph.ai/reference/errors/runtime-context-required-error/index.md)
- [InvalidPatchLifecycleState](https://docs.activegraph.ai/reference/errors/invalid-patch-lifecycle-state/index.md)

### RegistrationError

- [BehaviorNotFoundError](https://docs.activegraph.ai/reference/errors/behavior-not-found-error/index.md)
- [AmbiguousBehaviorError](https://docs.activegraph.ai/reference/errors/ambiguous-behavior-error/index.md)
- [ToolNotFoundError](https://docs.activegraph.ai/reference/errors/tool-not-found-error/index.md)
- [AmbiguousToolError](https://docs.activegraph.ai/reference/errors/ambiguous-tool-error/index.md)
- [IncompatibleRuntimeState](https://docs.activegraph.ai/reference/errors/incompatible-runtime-state/index.md)

### PackError

- [PackNotFoundError](https://docs.activegraph.ai/reference/errors/pack-not-found-error/index.md)
- [PackConflictError](https://docs.activegraph.ai/reference/errors/pack-conflict-error/index.md)
- [PackVersionConflictError](https://docs.activegraph.ai/reference/errors/pack-version-conflict-error/index.md)
- [PackSchemaViolation](https://docs.activegraph.ai/reference/errors/pack-schema-violation/index.md)

### Internal (framework-bug voice)

- [InternalEvaluatorError](https://docs.activegraph.ai/reference/errors/internal-evaluator-error/index.md)

## What's related

- [Concepts: Failure model](https://docs.activegraph.ai/concepts/failure-model/index.md) — the hierarchy and the events-not-exceptions principle.
- [Reference: Reason codes](https://docs.activegraph.ai/reference/reason-codes/index.md) — the stable `behavior.failed` / `tool.responded` / failed LLM attempt reason vocabulary.
- [API reference: Errors](https://docs.activegraph.ai/reference/api/errors/index.md) — the class hierarchy rendered from docstrings.
- [Cookbook: Debugging](https://docs.activegraph.ai/cookbook/debugging/index.md) — diagnostic workflows that build on the per-error catalog.