---
title: WorkflowNotRegisteredError
description: Thrown when a workflow function is not registered in the current deployment.
type: reference
summary: Catch WorkflowNotRegisteredError when a workflow function cannot be found during execution.
related:
  - /docs/errors/workflow-not-registered
  - /docs/api-reference/workflow-errors/step-not-registered-error
---

`WorkflowNotRegisteredError` is thrown when the runtime tries to execute a workflow function that is not registered in the current deployment. This is an infrastructure error — not a user code error. It typically means a run was started against a deployment that does not have this workflow (e.g., the workflow was renamed or moved), or there was a build/bundling issue.

When this error occurs, the run fails with a `RUNTIME_ERROR` error code.

```typescript lineNumbers
import { WorkflowNotRegisteredError } from "workflow/errors"
declare const error: unknown; // @setup

if (WorkflowNotRegisteredError.is(error)) { // [!code highlight]
  console.error("Workflow not registered:", error.workflowName);
}
```

## API Signature

### Properties

<TSDoc
definition={`
interface WorkflowNotRegisteredError {
  /** The name of the workflow function that was not found. */
  workflowName: string;
  /** The error message. */
  message: string;
}
export default WorkflowNotRegisteredError;`}
/>

### Static Methods

#### `WorkflowNotRegisteredError.is(value)`

Type-safe check for `WorkflowNotRegisteredError` instances. Preferred over `instanceof` because it works across module boundaries and VM contexts.

<Callout>
The `.is()` method works in server-side Node.js code (API routes, middleware). When checking the error from `run.returnValue`, use `WorkflowRunFailedError.is()` and inspect `error.cause` — the underlying error is deserialized from the event log.
</Callout>

```typescript
import { WorkflowNotRegisteredError } from "workflow/errors"
declare const error: unknown; // @setup

if (WorkflowNotRegisteredError.is(error)) {
  // error is typed as WorkflowNotRegisteredError
}
```

