How to convert legacy custom actions to API Request actions in Zapier
This how-to guide explains how Zapier is converting legacy custom actions to new API Request actions, and how you can prepare, review, and update your Zaps to keep your automations running smoothly.
The information below is based on Zapier’s official update about this migration and is designed to walk you through every step of the change.
What is changing in Zapier custom actions
Legacy custom actions in Zapier are being automatically converted to the newer API Request action type. These modern actions offer greater reliability, flexibility, and consistency across apps.
The migration affects:
- Any Zap step built with an older custom action interface.
- Any shared Zaps or Zap templates that rely on legacy custom actions.
- Zaps that were created in the past but are still turned on and using these older actions.
After conversion, you will see API Request actions in place of your previous legacy steps in the Zap editor.
Timeline for the Zapier migration
The migration from old custom actions to API Request actions in Zapier follows a phased schedule. Exact dates may evolve, but the process generally includes:
- Announcement of the upcoming migration and documentation of breaking changes.
- Automatic conversion of eligible legacy custom actions at scale.
- Post-migration review period for users to confirm their Zaps still work as expected.
Because this is an automated process, you should not wait until the last moment. Review your Zaps in Zapier early so that any adjustments you need to make can be completed before your automations are migrated.
How Zapier converts legacy custom actions
Zapier converts legacy custom actions into API Request actions by mapping existing configuration fields to the new structure. During this process, the system attempts to keep behavior consistent while using the latest functionality.
Key parts of the automated conversion include:
- Mapping HTTP method, endpoint URL, and request body into the API Request step.
- Preserving authentication where possible, including headers and tokens.
- Keeping field mappings from previous steps to avoid breaking downstream actions.
However, certain patterns used in old custom actions can cause breaking changes. The next section explains what to watch for and how to reduce risk inside Zapier.
Known breaking changes in Zapier’s migration
Some legacy behaviors cannot be replicated exactly in the new API Request actions. When Zapier runs the automated migration, you may see one or more of these changes:
1. Request URL and method differences in Zapier
If a legacy custom action used a dynamic URL, custom query string formatting, or unsupported HTTP methods, Zapier may adjust the configuration when converting to API Request. This can affect:
- Endpoints with path variables injected in non-standard ways.
- Custom encoding behavior in the query string.
- Use of methods that are no longer supported in the new framework.
After the migration, open each updated step and confirm that the URL, method, and request structure match what your API expects.
2. Request body and header handling in Zapier
Legacy custom actions sometimes allowed mixed or implicit handling of form data, JSON, and custom headers. In the new API Request actions, Zapier uses a clearer and more structured approach.
Potential breaking changes include:
- Body format changed from form-encoded to JSON, or vice versa.
- Headers that were automatically injected may now need to be configured explicitly.
- Fields that used to be optional becoming required, depending on how the new action is defined.
Compare a sample request made before migration to a new request after conversion in Zapier to verify that the payload and headers are equivalent.
3. Response handling and output fields in Zapier
When responses are parsed differently, downstream steps in Zapier can break. With the migration to API Request actions, you may notice:
- Changes in how nested JSON is exposed as output fields.
- Differences in field names or the paths of arrays and objects.
- Previously hidden fields becoming visible, or vice versa.
Open the “Test” section for each converted step and review the sample data. If any downstream step references a field that has changed, you will need to remap that field.
How to prepare your Zaps before conversion
To minimize disruption when Zapier converts your legacy custom actions, follow these preparatory steps:
- Identify affected Zaps
In your Zapier account, locate Zaps that use custom actions. Focus on mission-critical workflows that send or receive data from APIs via custom requests. - Export or document current settings
Take screenshots or keep written records of each legacy custom action, including:- URL, method, and authentication type.
- Body format and parameters.
- Headers and query parameters.
- Contact app owners if needed
If you rely on an external API, coordinate with the app or API owner to confirm acceptable request formats and to plan any needed changes in Zapier.
How to review your Zaps after conversion in Zapier
After the automated migration completes, you should systematically review your workflows. Use the following checklist inside Zapier:
- Open each converted step
Find API Request actions that were converted from legacy custom actions. Review the configuration to ensure the method, endpoint, authentication, and body match your documented settings. - Run tests on each action
Use the “Test” button in the Zap editor to send test requests. Confirm that:- The request is accepted by the API.
- The response contains all the data you expect.
- No errors or warnings appear in Zapier.
- Check downstream field mappings
Open each action that consumes data from the converted step. If any mapped fields are missing or renamed, remap them using the new output fields exposed by the API Request action. - Monitor Zap runs
After turning Zaps back on, monitor run history for a period of time. Look for spikes in errors or unexpected results and adjust your configuration in Zapier accordingly.
Troubleshooting issues after migration in Zapier
If a Zap stops working or behaves unexpectedly after legacy custom actions are converted, follow this troubleshooting workflow:
- Compare old and new requests
Use your documented legacy configuration and compare it with the live API Request configuration in Zapier. Pay close attention to URL paths, request bodies, and headers. - Use API logs
If your API or external service provides logs, inspect recent requests. Check:- HTTP status codes.
- Error messages.
- Any mismatch in parameters or payload format.
- Adjust the API Request configuration
Update the action step to align with the API requirements. You may need to:- Switch between JSON and form-encoded bodies.
- Add or modify headers.
- Update dynamic URL segments or query strings.
- Re-test and validate downstream steps
After adjustments, retest the step and verify that all downstream steps in Zapier still receive the correct data.
Where to find the official Zapier migration details
For the exact list of breaking changes, supported patterns, and the most current migration timeline, review the official documentation from Zapier. You can access it here: Zapier legacy custom action conversion update.
If you manage complex automations or many Zaps across teams, you may also want strategic help with planning changes and documenting your integrations. A consulting partner such as Consultevo can support broader process reviews and optimization while you transition to the new API Request actions.
Next steps for maintaining reliable Zaps in Zapier
To keep your automations reliable after the migration to API Request actions, consider the following ongoing practices in Zapier:
- Regularly audit Zaps that use API requests or advanced custom logic.
- Document every integration’s request and response schema.
- Use test accounts or staging environments when changing critical Zaps.
- Monitor Zap run history to catch issues early after any update.
By understanding how legacy custom actions are converted and proactively managing the transition in Zapier, you can avoid downtime, protect data accuracy, and take advantage of the more powerful and maintainable API Request actions going forward.
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