Apply this guide to your situation
This answer covers “[WPO-013] Enable and verify HTTP compression without double-compressing”. Read it with the summary and confirm that the symptom and service match what you are experiencing. Available options can vary by plan and account setup.
- Before changing anything, note what you expected, what happened and roughly when. Check whether the issue affects one page or the whole service.
- Save the full error message and note recent changes. Hide passwords, access codes, personal data and keys before sharing screenshots or logs.
- If a step requires administrator access, restarting services or editing server files, stop if you do not administer that server. Send support the service name, error and checks you have already made.
L3 technical diagnosis
User symptoms
HTML, CSS and JavaScript transfer much more data than expected.
Observed code or message
Missing or duplicated `Content-Encoding`; client reports `ERR_CONTENT_DECODING_FAILED`Likely root cause
Compression may be disabled, a MIME type excluded, both upstream and proxy compressing, or a cache ignoring `Accept-Encoding`, negating savings or corrupting responses.
Likely-cause and resolution matrix
Follow a branch only when evidence supports it. A symptom may have more than one cause; do not change layers by guesswork.
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Prerequisites
- Authorised access to the affected site, repository or service metrics.
- A reproducible URL and timestamp; use staging for infrastructure changes.
- A backup or rollback method for configuration and deployments.
Important warnings
- Inspection commands do not authorise production changes. Do not run load tests or global purges without an approved plan.
- Never store private responses in shared caches. Server changes in Anayil Panel depend on the controls available for the service and may require its administrator/provider.
Step-by-step walkthrough
1. Reproduce and narrow the issue
curl -sSI -H 'Accept-Encoding: br,gzip' https://example.com/assets/app.js | grep -iE '^(content-encoding:|content-length:|vary:)'Missing or duplicated `Content-Encoding`; client reports `ERR_CONTENT_DECODING_FAILED`
2. Apply the appropriate correction
3. Verify the experience
The improvement is reproducible on the affected route and profile with no new functional errors.
Troubleshooting & Solutions
Missing or duplicated `Content-Encoding`; client reports `ERR_CONTENT_DECODING_FAILED`
Root cause: Compression may be disabled, a MIME type excluded, both upstream and proxy compressing, or a cache ignoring `Accept-Encoding`, negating savings or corrupting responses.
Resolution: Enable compression at one layer or explicitly define ownership across layers. Include appropriate text MIME types; do not recompress formats that are already compressed. Ensure the cache varies representations by `Accept-Encoding`.
Rollback and recovery plan
Roll back only the changed directive, dependency or release using the recorded value. If 5xx errors, data exposure or session failures occur, have the operator disable the new rule and retain redacted logs for analysis.
Related runbooks in this category:
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