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

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Issues

You cannot change the step order of a 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: 
HTTP status 400. Incompatible step name. Expected <STEP_NAME>, got <STEP_NAME>

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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

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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 section.