---
title: workflow/errors
description: Semantic error types thrown by the Workflow SDK and its storage backends.
type: overview
summary: Explore the error classes exported from workflow/errors for handling workflow failures.
related:
  - /docs/foundations/errors-and-retries
---

# workflow/errors



API reference for the error classes exported from the `workflow/errors` package.

All errors extend [`WorkflowError`](/docs/api-reference/workflow-errors/workflow-error), so you can catch any SDK error with a single `instanceof` check, or narrow to a specific class for fine-grained handling.

## Base Classes

<Cards>
  <Card href="/docs/api-reference/workflow-errors/workflow-error" title="WorkflowError">
    Base class for all workflow error types.
  </Card>

  <Card href="/docs/api-reference/workflow-errors/workflow-world-error" title="WorkflowWorldError">
    Base error for failures from workflow storage backends.
  </Card>
</Cards>

## Registration Errors

<Cards>
  <Card href="/docs/api-reference/workflow-errors/workflow-not-registered-error" title="WorkflowNotRegisteredError">
    Thrown when a workflow function is not registered in the current deployment.
  </Card>

  <Card href="/docs/api-reference/workflow-errors/step-not-registered-error" title="StepNotRegisteredError">
    Thrown when a step function is not registered in the current deployment.
  </Card>
</Cards>

## Run Errors

<Cards>
  <Card href="/docs/api-reference/workflow-errors/workflow-run-not-found-error" title="WorkflowRunNotFoundError">
    Thrown when operating on a workflow run that does not exist.
  </Card>

  <Card href="/docs/api-reference/workflow-errors/workflow-run-failed-error" title="WorkflowRunFailedError">
    Thrown when awaiting the return value of a failed workflow run.
  </Card>

  <Card href="/docs/api-reference/workflow-errors/workflow-run-cancelled-error" title="WorkflowRunCancelledError">
    Thrown when awaiting the return value of a cancelled workflow run.
  </Card>

  <Card href="/docs/api-reference/workflow-errors/workflow-run-not-completed-error" title="WorkflowRunNotCompletedError">
    Thrown when requesting the result of a workflow run that has not completed yet.
  </Card>

  <Card href="/docs/api-reference/workflow-errors/workflow-runtime-error" title="WorkflowRuntimeError">
    Thrown when the workflow runtime encounters an execution error, such as serialization failures or timeouts.
  </Card>

  <Card href="/docs/api-reference/workflow-errors/run-expired-error" title="RunExpiredError">
    Thrown when a workflow run has expired and can no longer be operated on.
  </Card>

  <Card href="/docs/api-reference/workflow-errors/run-not-supported-error" title="RunNotSupportedError">
    Thrown when a workflow run requires a newer workflow spec version than the installed SDK supports.
  </Card>
</Cards>

## Hook Errors

<Cards>
  <Card href="/docs/api-reference/workflow-errors/hook-not-found-error" title="HookNotFoundError">
    Thrown when resuming a hook that does not exist.
  </Card>

  <Card href="/docs/api-reference/workflow-errors/hook-conflict-error" title="HookConflictError">
    Thrown when creating a hook with a token that is already in use by another workflow run.
  </Card>
</Cards>

## Backend Errors

<Cards>
  <Card href="/docs/api-reference/workflow-errors/throttle-error" title="ThrottleError">
    Thrown when a request is rate-limited by the workflow backend.
  </Card>

  <Card href="/docs/api-reference/workflow-errors/entity-conflict-error" title="EntityConflictError">
    Thrown when a storage operation conflicts with the current entity state.
  </Card>

  <Card href="/docs/api-reference/workflow-errors/too-early-error" title="TooEarlyError">
    Thrown when a request is made before the system is ready to process it.
  </Card>
</Cards>


## Sitemap
[Overview of all docs pages](/sitemap.md)