Building Resilient Workflows: Error Handling Strategies

Workflows can fail for many reasons, bad data, unreachable systems, malformed inputs, or bugs in handler code. But failure doesn’t have to mean everything stops. In fact, robust workflows are built with failure in mind.

This guide introduces you to practical techniques for handling errors inside workflows using Handlers and Routines. You'll learn how to:

• Proactively branch logic when a handler fails
• Capture and route errors to human responders
• Design recursive retry patterns using routines
• Separate user-facing workflows from administrative recovery tasks

Whether you're building for a self-service portal or managing critical system automations, these patterns will help ensure your workflows continue running, even when parts of them don’t.

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What Is a Handler?

Handlers are reusable Ruby-based components that:

• Accept inputs
• Run a specific function (e.g., submit a form, call an API)
• Return outputs or errors

They form the core building blocks of many workflow nodes.

By default, when a handler fails, it may stop the workflow. But with intentional design, handlers can return structured errors that your workflow can evaluate and act on, allowing for retry logic, fallback branches, or notification triggers instead of hard stops.

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Want to learn more?

Check out Using Handlers for a deeper dive into handler usage and types.

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Branching on Error Outputs

Instead of halting a workflow, handlers can return an error as part of their result, allowing your workflow to conditionally route based on that outcome.

Examples:

• If a handler fails to create a user, route to a branch that creates the user, then retries
• If an API returns "404 Not Found", route the logic to notify an admin

This enables graceful failure recovery, especially when external systems are unreliable.

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Creating Retry Paths with External Input

One powerful pattern for managing errors is designing routines that allow end-user intervention without requiring access to the workflow builder or admin tools.

Here’s how it works:

1. Wrap Handlers in a Routine
   Each handler is called from inside a routine that mimics its inputs and outputs. This wrapper allows you to evaluate errors and apply retry logic without modifying the workflow tree.

2. Detect Errors
   If the handler fails, the routine captures the error and calls a secondary error-handling routine.

3. Generate a Retry Opportunity
   The error-handling routine might:

   • Create a support ticket
   • Trigger a notification
   • Log the issue in a custom dashboard
   • Offer correction options to an admin or service team

4. Re-call the Original Routine (Recursively)
   After the external party updates the data or selects a retry action, the routine calls itself again, passing in the updated or corrected inputs.

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This recursive design ensures that once the error is addressed, the workflow can resume its original path without restarting entirely.

Front-End Considerations

To make this more user-friendly for admins or business users:

• You'll need custom front-end components (e.g., in your portal) to surface the retry options
• Use permissions to control who can view or act on these issues
• Surface relevant context like error details, submission IDs, and retry options

This approach is ideal in SaaS environments or large organizations, where giving everyone access to the workflow engine isn't feasible, but fixing issues quickly is essential.

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Pro Tip: Blend this strategy with automated branching to cover both expected and unexpected failure modes.

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Engine-Level Retry as a Fallback

If the handler isn't coded to return errors gracefully, or no catch routine exists, use the built-in error management tools:

• Navigate to the run and view the failed node
• Use options like Retry Task or Skip Task
• Optionally edit inputs or results before retrying

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Use caution with retries — especially if the handler already made a change like submitting a form or sending a message. Retrying could duplicate those actions.

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When to Use Each Strategy

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What’s Next?

• Debugging Workflows with the Runs Tab
• Understanding Workflow Errors
• Writing Reusable Routines