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Fix Cloudflare 521 Error: DNS Configuration Problem - Passing Env Vars to Docker Compose Build-How to Fix an Nginx Redirect Loop: Step-by-Step

Updated 2026-07-28 16:06:26developer-tools

Fix Cloudflare 521 Error: DNS Configuration Problem - Passing Env Vars to Docker Compose Build-How to Fix an Nginx Redirect Loop: Step-by-Step

Prepare

Execute

Validate

Document

Operational follow-up

Record the exact option, command, or setting that changed the result.
Keep a rollback note if the workflow affects shared files or team settings.

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