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520
Cloudflare Error 520: Web server returned an unknown error
Error↻ Retryable · exponential backoffHTTP 520 Web Server Returned an Unknown ErrorCDN / Edge
TL;DR · 10-second read
The origin returned an empty, invalid or reset response (crash, oversized headers > 128 KB, connection reset). Check origin error logs at the Ray ID timestamp.
Identify: does your log match?
What you see · exact log / response
Error 520 Ray ID: 8d2f9e5c7d8a3f24 • 2026-10-13 03:18:27 UTC Web server is returning an unknown error
Fix
Being written
Copy-paste fixes for 520 are in the enrichment queue
The summary above is verified. Paste your full trace into the decoder for a diagnosis now.
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Last verified 2026-10-13 · Source: Cloudflare 1xxx and 5xx error reference · Official docs ↗ · ~18,100 searches/mo