Nginx rewrite loop cache or propagation drift response

When this happens

Use this when the panel says fixed but some users still see the old error. Do not stop at the screen message; validate browser cache, CDN cache, DNS TTL, panel propagation, and stale application cache first.

Symptom checklist

• rewrite loop appears repeatedly in the Nginx UI or logs.
• server_name, location, proxy_pass, upstream logs differs between successful and failed requests.
• The issue appears only after separating Nginx layer from backend application.
• It often follows deploys, permission changes, configuration edits, or data refreshes.

Likely causes

• rewrite loop specifically changes the investigation surface for Nginx: verify the exact failing object, route, user, and timestamp before applying the broader pattern.
• A broad rewrite rule captures requests before a more specific rule can run.
• Directory-level .htaccess context changes how RewriteRule patterns are evaluated.
• HTTP-to-HTTPS, slash, or canonical-host rules redirect back to each other.
• The front controller route hides real static files or API endpoints.
• AllowOverride or module loading differs between local and production Apache.
• For the cache or propagation drift case, the first useful clue is browser cache, CDN cache, DNS TTL, panel propagation, and stale application cache.

First 1-minute checks

1. Write down the first failure time, latest change, affected user, path, and object ID.
2. Compare server_name, location, proxy_pass, upstream logs for success and failure in the same window.
3. Test the hypothesis: rewrite failure caused by rule order, missing RewriteBase, recursive redirects, directory context, or front-controller routing.
4. Classify this as cache or propagation drift: browser cache, CDN cache, DNS TTL, panel propagation, and stale application cache.
5. Capture current values before changing configuration.

First evidence

Treat rewrite loop as a cache or propagation drift case. First collect evidence for browser cache, CDN cache, DNS TTL, panel propagation, and stale application cache.

Output examples

Normal output

Fresh requests and DNS answers show the same intended value from multiple networks.

Failing output

Only one resolver, browser, CDN edge, or cached object still returns the old value.

Output-to-action branches

• The panel says fixed but some users still see the old error.
  Separate DNS, CDN, browser, and application cache, then purge only the stale layer.
• The working and failing outputs differ.
  Act on the differing layer first: For rewrite loop, 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 repeatedly edit correct DNS records just because a stale resolver is still visible.
• 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 "rewrite loop" ./logs

nginx -T | grep -n "server_name\|location\|proxy_pass"

tail -n 200 /var/log/nginx/error.log

curl -Iv http://127.0.0.1:3000

ss -lntp

apachectl -M | grep rewrite

apachectl -S

grep -R "RewriteRule\|RewriteCond\|return 301\|rewrite" . /etc/apache2 /etc/nginx

curl -IL https://example.com/path

curl -I https://example.com -H 'Cache-Control: no-cache' && dig +trace example.com

Fix order

1. Record the full rewrite loop message, failing URL, user, object ID, and latest change.
2. Collect issue-specific evidence for rewrite failure caused by rule order, missing RewriteBase, recursive redirects, directory context, or front-controller routing.
3. Compare the failing case with a successful case before editing settings.
4. If this is the cache or propagation drift branch, Separate DNS, CDN, browser, and application cache, then purge only the stale layer.
5. Re-check with the same command and URL, then record the normal output.

Actions by cause

• For rewrite loop, apply the fix only after reproducing the same condition and saving the before/after evidence for this exact code.
• Print effective Apache or Nginx rules and check order before editing application routes.
• Add stop conditions for existing files, directories, and already-canonical hosts.
• Test redirects with curl -I until only one final location remains.
• Move broad front-controller rules below asset and API exceptions.
• Confirm rewrite modules and AllowOverride are enabled in the active virtual host.
• For the cache or propagation drift branch, Separate DNS, CDN, browser, and application cache, then purge only the stale layer.

Evidence links

• NGINX Admin Guide official
• NGINX reverse proxy guide 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 Nginx rewrite loop.

Environment-specific checks

• Shared hosting, proxies, VPNs, or CDN layers can change Nginx layer from backend application results.
• Do not trust only the Nginx 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 server_name, location, proxy_pass, upstream logs.
• Add location priority, proxy headers, and upstream timeout 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

• Nginx 502 Bad Gateway upstream connection failure
• Nginx 301 loop fix note
• Nginx 413 fix note
• Nginx 301 loop fix note 2
• Nginx 413 fix note 2
• Nginx 301 loop fix note 3
• Nginx 413 fix note 3
• Nginx 301 loop fix note 4