Trying to create a PR from a fork which does not exist with a user access token (UAT) results in a 500 and no info

[xmo-odoo]

🏷️ Discussion Type

Bug

💬 Feature/Topic Area

API

Body

endpoint: POST /repos/{owner}/{repo}/pulls
parameters:

• a base which exists
• a head in compound form (user:branch), user exists but has not forked the repository
• a title

classic PAT

this results in a 422 "Validation Failed" with the error details {'code': 'invalid', 'field': 'head', 'resource': 'PullRequest'}

UAT

this results in an error 500 with no body

complementary information

• the base repository is owned by an organization
• the application is installed in both the organization and the user accounts
• the user access token from the user's authorization
• after creating the fork and the HEAD branch, using the same authentication, creating the PR succeeds

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[AhmadHassan-BTed]

Yess : ( that 500 error is 100% a backend crash on GitHub's side.

The UAT auth pipeline is hitting an unhandled exception when trying to check permissions for a fork that doesn't exist. It just crashes before it even reaches the normal 422 validation logic that classic PATs use.

Until they patch it, your only real option is to just add a quick preflight API call in your code to verify the fork actually exists before you hit the POST endpoint. Sucks you have to write extra code just to avoid their server crash, but that's the only reliable way around it right now.

[youssef509]

Based on your description, this looks like inconsistent error handling. The same request returns a 422 Validation Failed when using a classic PAT, so I'd expect a user access token to return the same validation error if the head repository doesn't exist. A 500 Internal Server Error suggests the server isn't gracefully handling this case.

Since the request succeeds with the same UAT after the fork and branch are created, it doesn't appear to be a general permissions issue. It seems more likely that the lookup of the head repository is failing in the UAT code path and isn't being translated into the expected client-facing validation error.