Diagnosing Stackblitz-GitHub Sync Issues

Recognizable condition

Changes pushed to GitHub do not appear in the Stackblitz editor, or pull and push from Stackblitz to GitHub fail with authentication or permission errors. Importing a GitHub repository hangs, times out, or opens an empty workspace. Switching branches in Stackblitz does not update the file tree or commit history.

Cause and symptom table

Ordered checks

1. Verify sync status indicator

   In the Stackblitz UI, bottom-left corner, check the GitHub badge. It should read Up to date or show a recent sync timestamp. Error or Not connected indicates auth or network issues.

2. Check personal access token scopes

   In GitHub settings for the integration used by Stackblitz, confirm the token has repo and workflow scopes. Insufficient scopes cause silent sync failures. Regenerate the token with required scopes and re-link in Stackblitz Account → GitHub if needed. Risk: revoking a token disconnects other integrations.

3. Test network reachability to GitHub API

   From a terminal with internet access, run:

   curl -I https://api.github.com/zen

   Expected check: connection succeeds. A timeout or connection refused suggests firewall or IP allow-list blocking. Verify outbound connections to api.github.com on port 443 are permitted.

4. Assess repository size and composition

   From a terminal with a PAT, run:

   curl -H "Authorization: token YOUR_PAT" https://api.github.com/repos/OWNER/REPO

   Check the size field. If repository size exceeds ~1 GB or contains files >100 MB, import may fail or degrade. Large binaries should be moved to Git LFS or excluded.

5. Validate branch state in Stackblitz

   In Stackblitz, open the terminal with Ctrl+Shift+` and run:

   git status

   Check that the branch name matches the UI selection and working tree is clean. If detached HEAD is shown, run:

   git checkout BRANCH_NAME

   Then run:

   git pull origin BRANCH_NAME

   Confirm the file tree updates.

Fixes tied to findings

• Missing or expired PAT scopes: Regenerate a token with repo and workflow scopes, then re-authorize in Stackblitz. After re-authenticating, push a test commit to GitHub and confirm the change appears in the Stackblitz editor within 10-15 seconds.
• Network block: Allow outbound traffic to api.github.com. After change, verify sync status indicator reads Up to date.
• Large repository: Avoid importing monorepos or repositories with large binary files. Create a shallow clone for testing or move large assets to Git LFS, then re-import.
• Stale branch state: Run git fetch origin then git checkout BRANCH_NAME in the Stackblitz terminal. Verify file tree and git log reflect the selected branch HEAD commit.

Escalation criteria

Escalate if sync status remains Error after re-authentication with correct scopes, network reachability is confirmed, and repository size is under limits. Also escalate if branch switches consistently leave a detached HEAD despite manual checkout, or if import repeatedly times out for repositories well under size limits. Provide the workspace URL, repository size, token scope confirmation, and sync status screenshots.

Limitations

Stackblitz has practical limits for repository size and file size. Very large repositories, monorepos, and large binaries can cause slow loading or import failures even with correct authentication. Sync is best-effort; transient GitHub API latency can delay updates.