Apache .htaccess 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

• .htaccess appears repeatedly in the Apache UI or logs.
• DocumentRoot, Directory permissions, AllowOverride, error_log differs between successful and failed requests.
• The issue appears only after separating Apache config errors from application errors.
• It often follows deploys, permission changes, configuration edits, or data refreshes.

Likely causes

• .htaccess specifically changes the investigation surface for Apache: 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 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 DocumentRoot, Directory permissions, AllowOverride, error_log 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 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 .htaccess 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 .htaccess, 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 ".htaccess" ./logs

apachectl -S

apachectl configtest

grep -R ".htaccess" /var/log/apache2

find /var/www -maxdepth 2 -type d -ls

apachectl -M | grep rewrite

apachectl -S

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

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

curl -Iv https://example.com --resolve example.com:443:ORIGIN_IP

Fix order

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

Evidence links

• Apache HTTP Server documentation official
• Apache mod_rewrite documentation 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 Apache .htaccess.

Environment-specific checks

• Shared hosting, proxies, VPNs, or CDN layers can change Apache config errors from application errors results.
• Do not trust only the Apache 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 DocumentRoot, Directory permissions, AllowOverride, error_log.
• Add vhost, Directory, mod_rewrite, and file permissions 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

• Apache 403 Forbidden DocumentRoot permission error
• Apache .htaccess fix note
• Apache failed fix note
• Apache .htaccess fix note 2
• Apache failed fix note 2
• Apache .htaccess fix note 3
• Apache failed fix note 3
• Apache .htaccess fix note 4