Git non-fast-forward specific path failure response

When this happens

Use this when only one page, endpoint, static asset, or api route fails. Do not stop at the screen message; validate the route, rewrite rule, API path, host header, and upstream mapping first.

Symptom checklist

• non-fast-forward appears repeatedly in the Git UI or logs.
• HEAD, upstream, rebase state, hooks, LFS differs between successful and failed requests.
• The issue appears only after separating local worktree issue from remote rejection.
• It often follows deploys, permission changes, configuration edits, or data refreshes.

Likely causes

• non-fast-forward specifically changes the investigation surface for Git: verify the exact failing object, route, user, and timestamp before applying the broader pattern.
• Local history diverged from the remote branch.
• A rebase, merge, or submodule operation left the index in a partial state.
• Large files or line endings changed outside the repository policy.
• A tag or protected branch already exists on the remote.
• Authentication succeeds but remote policy rejects the update.
• For the specific path failure case, the first useful clue is the route, rewrite rule, API path, host header, and upstream mapping.

First 1-minute checks

1. Write down the first failure time, latest change, affected user, path, and object ID.
2. Compare HEAD, upstream, rebase state, hooks, LFS for success and failure in the same window.
3. Test the hypothesis: Git workflow failure caused by divergent history, unresolved index state, LFS/large files, line endings, submodules, tags, or remote policy.
4. Classify this as specific path failure: the route, rewrite rule, API path, host header, and upstream mapping.
5. Capture current values before changing configuration.

First evidence

Treat non-fast-forward as a specific path failure case. First collect evidence for the route, rewrite rule, API path, host header, and upstream mapping.

Output examples

Normal output

Working and failing paths use the intended host, status, and upstream.

Failing output

Only one route changes status, redirect target, content type, or upstream.

Output-to-action branches

• Only one page, endpoint, static asset, or API route fails.
  Compare a working path and failing path, then fix routing, rewrite, upload limit, or upstream mapping.
• The working and failing outputs differ.
  Act on the differing layer first: For non-fast-forward, apply the fix only after reproducing the same condition and saving the before/after evidence for this exact code.
• Command output is normal but users still fail.
  Separate browser cache, cookies, permissions, and network location before declaring it fixed.

Do not do this

• Do not clear every cache before proving the route mapping.
• Do not change multiple layers before identifying the failing layer.
• Do not delete production data, grant broad permissions, or disable security controls as a first response.

Evidence quality

Auto-generated operator draft: includes issue-specific causes, commands, output branches, and unsafe-action warnings. Official-source links and real incident validation are queued for enrichment.

Commands to run first

grep -R "non-fast-forward" ./logs

git status --short --branch

git log --oneline --decorate -5

git remote -v

git ls-files -s | head

git status --short --branch

git log --oneline --decorate -5

git ls-files -u

git remote -v

curl -I https://example.com/failing-path && curl -I https://example.com/working-path

Fix order

1. Record the full non-fast-forward message, failing URL, user, object ID, and latest change.
2. Collect issue-specific evidence for Git workflow failure caused by divergent history, unresolved index state, LFS/large files, line endings, submodules, tags, or remote policy.
3. Compare the failing case with a successful case before editing settings.
4. If this is the specific path failure branch, Compare a working path and failing path, then fix routing, rewrite, upload limit, or upstream mapping.
5. Re-check with the same command and URL, then record the normal output.

Actions by cause

• For non-fast-forward, apply the fix only after reproducing the same condition and saving the before/after evidence for this exact code.
• Inspect branch, index, and remote state before editing files.
• Resolve conflicts once, then continue or abort the operation deliberately.
• Move large assets to LFS or remove them from history before pushing.
• Normalize line endings with repository attributes.
• Fetch tags and remote branch rules before retrying.
• For the specific path failure branch, Compare a working path and failing path, then fix routing, rewrite, upload limit, or upstream mapping.

Evidence links

• Git documentation official
• GitHub authentication troubleshooting official

Verification metadata

• operator-draft
• official-reference-linked
• 2026-07-23

Update queue

• Review cadence
  weekly-source-review
• Next enrichment
  Add one official-source check and one real output example for Git non-fast-forward.

Environment-specific checks

• Shared hosting, proxies, VPNs, or CDN layers can change local worktree issue from remote rejection results.
• Do not trust only the Git UI; compare command output.
• Japanese hosting panels may show completion before DNS or SSL fully propagates.
• Test from both office and external networks.

Prevent it next time

• Store normal examples for HEAD, upstream, rebase state, hooks, LFS.
• Add rebase/merge cleanup, upstream reset, LFS tracking, hook logs to the release checklist.
• Keep recurring errors in the same note format.
• Split alerts by error rate, latency, certificates, disk, and permission changes.

Related notes

• Git merge conflict first triage response
• Git non-fast-forward first triage response
• Git detached HEAD first triage response
• Git permission denied publickey first triage response
• Git large file first triage response
• Git rebase conflict first triage response
• Git submodule first triage response
• Git line endings first triage response