# Error Handling - Temporal Nexus

> Learn about error handling for Temporal Nexus.

Nexus Operations can return errors for a caller Workflow to handle.
Errors from an asynchronous Operation's underlying Workflow propagate back to the caller.

## Errors in Nexus handlers

Nexus handlers may return [different error types](/references/failures#nexus-errors).
By default, handler errors are retryable unless they are:

- [Application Failures](/references/failures#nexus-errors) explicitly marked as non-retryable.
- [Nexus Operation errors](/references/failures#nexus-errors) that resolve an Operation as failed or canceled.
- [Non-retryable Nexus errors](/references/failures#non-retryable-nexus-errors).

When the caller's Nexus Machinery receives an error:

- **Non-retryable** - A [NexusOperationFailed](/references/events#nexusoperationfailed) event is added to the caller's Event History.
- **Retryable** - The Nexus Machinery [automatically retries](/nexus/operations#automatic-retries). These errors surface in [Pending Operations](/nexus/execution-debugging/#pending-operations).

> **💡 Tip:**
>
> Return a [specific Nexus error type](/references/failures#nexus-errors) to avoid infinite retries.
> See [errors in Nexus Operations](/references/failures#errors-in-nexus-operations) for additional details.
>

## Nexus error handling in caller Workflows

When a Nexus Operation fails, the caller receives a Nexus Operation Failure containing the operation name, token, and failure reason.
The cause field indicates the type of error (for example, Application Error or Canceled Error).

> **💡 Tip:**
> RESOURCES
>
> - [Errors in Nexus Operations](/references/failures#errors-in-nexus-operations)
> - [Nexus Errors](/references/failures#nexus-errors)
> - [Nexus Operation Failures](/references/failures#nexus-operation-failure)
>