---
title: WorkflowRuntimeError
description: Thrown when the workflow runtime encounters an execution error, such as serialization failures or timeouts.
type: reference
summary: Catch WorkflowRuntimeError for runtime-level failures like unserializable values or workflow timeouts.
related:
  - /docs/foundations/serialization
  - /docs/foundations/errors-and-retries
---

# WorkflowRuntimeError



`WorkflowRuntimeError` is thrown when the workflow runtime encounters an error executing a workflow. Common causes include:

* Values crossing the workflow/step boundary that cannot be serialized
* Workflow execution timeouts
* Invalid runtime state, such as misconfigured streams

```typescript lineNumbers
import { WorkflowRuntimeError } from "workflow/errors"
declare function runWorkflowOperation(): Promise<void>; // @setup

try {
  await runWorkflowOperation();
} catch (error) {
  if (WorkflowRuntimeError.is(error)) { // [!code highlight]
    console.error("Workflow runtime error:", error.message);
  }
}
```

## API Signature

### Properties

<TSDoc
  definition={`
interface WorkflowRuntimeError {
/** The error message. */
message: string;
/** The underlying cause, when provided. */
cause?: unknown;
}
export default WorkflowRuntimeError;`}
/>

### Static Methods

#### `WorkflowRuntimeError.is(value)`

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

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

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


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