Cannot push to fork's pull request branch even though maintainers are allowed to edit the pull request

[spenserblack]

🏷️ Discussion Type

Bug

Body

Has anyone else experienced this?

Seeing the check mark and note

Maintainers are allowed to edit this pull request.

I would assume that would mean that I could open the PR in a Codespace, make changes, and push those changes to the PR's source branch. What actually happens is that I get a 403 error.

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[ThePhantom-S]

This 403 error persists because the "Allow maintainer edits" feature is scoped—it does not grant full repository write access. It often fails with Codespaces or Git clients due to security protocols, LFS restrictions, or credential mismatches.

1. Identify the Cause

   Git LFS: If the repo uses LFS, you cannot push to a contributor's fork due to storage/billing restrictions.

   Protocol Mismatch: The GitHub Web Editor uses an authenticated API bypass; Git clients (and Codespaces) use standard SSH/HTTPS authentication, which requires explicit write permission to the remote fork.

2. Immediate Fixes

   Use the Web Editor: For small changes, edit the files directly on GitHub.com. This avoids the 403 error by using the platform's internal edit bypass.

   Ask the Contributor: If changes are complex, request the contributor to push the necessary updates to their own branch.

   Fork and Push:

    Create your own fork of the original repository.
   
    Merge the contributor's branch into your fork.
   
    Make your changes there.
   
    Open a new PR from your fork to the base repository.
   

3. Verify Remote Access

If you must use the command line, ensure you are pushing to the contributor's fork remote (not the base repo):

Check your remotes: git remote -v

Ensure you have added the contributor's fork: git remote add contributor <fork-url>

Attempt the push: git push contributor <branch-name>

[Vance1832]

The "Allow edits from maintainers" checkbox and the 403 you're hitting in Codespaces are actually two separate permission systems, which is the source of the confusion:

Why it fails:

• "Allow edits from maintainers" grants push access to the fork branch for maintainers authenticating with their own personal credentials (a PAT, SSH key, or the GitHub web editor's session).
• A Codespace, by contrast, authenticates git operations using an automatically-generated, repo-scoped token (the Codespaces token / GITHUB_TOKEN-style credential injected by the codespace). That token is scoped to the repository the codespace was created against — it does not automatically inherit the "maintainer can push to this specific fork branch" grant, even though you're a maintainer. That grant only applies to credentials tied to your account directly, not to the codespace's own service-issued token.

This has been reported as a regression by GitHub staff in a related thread (https://github.com/orgs/community/discussions/36357), so you're not missing a setting — it's a real gap in how Codespaces' credential helper resolves fork permissions.

Workaround that reliably works:

1. Inside the Codespace terminal, re-authenticate git with your own account instead of the codespace's default token:

   gh auth login
   gh auth setup-git
   

   This swaps the credential helper to use your personal gh session instead of the codespace-scoped token.
2. Then push normally:

   git push <fork-remote> <branch-name>
   

If you don't want to re-auth, pushing from your local machine (where your normal SSH key or PAT is already configured) instead of from within the Codespace will also work immediately, since local git isn't using the codespace's scoped token.