Troubleshooting 404 Errors When Using the Async HTTP Request Block in Workflows

Overview

If you receive a 404 response when posting to a Workflow’s callbackUrl from an Async HTTP Request block, the issue typically stems from permissions or callback validity.

Common Causes

1. API Key Permissions

   • The API key used to send the callback must have permission to interact with the workflow run.

   • If your key only has the User role, you may receive a 404 even though the callback URL is correct.

   • This happens most often when the workflow has team-based restrictions or requires elevated roles.

2. Callback URL Validity

   • Each callbackUrl is unique to a single workflow run and block.

   • Reusing a callback URL from a previous or completed run will result in a 404 Not Found.

How to Resolve

• Check your key’s permissions:
  Try using an API key with Admin or a custom role that’s included in the workflow’s run restrictions.

• Alternatively, use a Personal Access Token (PAT):
  A PAT from a user who is authorized to run the workflow will work even if the workflow has restrictions.

• Confirm the callback URL:
  Make sure you’re using the callback URL from the current, active workflow run, and that the workflow is still paused on the Async HTTP block when you send the POST request.