# Update a Workflow

Workflows are composed of multiple steps. When you modify workflow code, it's important to consider how these changes might affect in-progress workflows.

## Issues

You cannot change the step order of an existing workflow.

If your code changes remove or reorder existing steps, in-progress workflows may attempt to continue from a point that no longer exists. This can lead to workflow failures, typically resulting in the following error:

```bash
HTTP status 400. Incompatible step name. Expected <STEP_NAME>, got <STEP_NAME>
```

## Safe changes

Updating workflow code is safe in the following cases:

- No active workflow runs exist
- Only new steps are added to the end of the workflow

## Guidelines for updating workflows

Consider the following approaches when updating your workflow code:

- **Accept potential failures:** If you're fine with in-progress workflows failing, you can make any code changes.
- **Use a different route:** To avoid failures, consider serving the updated workflow under a different route.
- **Stop traffic before deployment:** If you need to keep the same route, stop all traffic before deploying new code.
- **Add steps only:** If stopping traffic is not an option, limit your changes to adding new steps at the end of the workflow.

For a deeper understanding of these limitations, see our [how workflows work](/workflow/basics/how) section.