Git non-fast-forward proxy versus origin split response

When this happens

Use this when a cdn, load balancer, reverse proxy, or waf sits in front of the service. Do not stop at the screen message; validate whether the edge/proxy or the origin server creates the failure 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 proxy versus origin split case, the first useful clue is whether the edge/proxy or the origin server creates the failure.

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 proxy versus origin split: whether the edge/proxy or the origin server creates the failure.
5. Capture current values before changing configuration.

First evidence

Treat non-fast-forward as a proxy versus origin split case. First collect evidence for whether the edge/proxy or the origin server creates the failure.

Output examples

Normal output

Direct origin and routed proxy return equivalent status and headers.

Failing output

Origin succeeds but proxy fails, or proxy succeeds while direct origin exposes the real backend error.

Output-to-action branches

• A CDN, load balancer, reverse proxy, or WAF sits in front of the service.
  Test direct origin and routed traffic separately, then change only the layer that differs.
• 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 assume the CDN error code is the application root cause.
• 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 -Iv https://example.com --resolve example.com:443:ORIGIN_IP

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 proxy versus origin split branch, Test direct origin and routed traffic separately, then change only the layer that differs.
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 proxy versus origin split branch, Test direct origin and routed traffic separately, then change only the layer that differs.

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