HTTP 520 Web Server Returned an Unknown Error vs 524 A Timeout Occurred
Both HTTP 520 (Web Server Returned an Unknown Error) and 524 (A Timeout Occurred) belong to the 5xx Server Error category. 520 indicates that cloudflare-specific. The origin server returned an unexpected response that Cloudflare could not process. Meanwhile, 524 means that cloudflare-specific. A TCP connection was established but the origin didn't respond with an HTTP response in time.
Description
Cloudflare-specific. The origin server returned an unexpected response that Cloudflare could not process.
When You See It
When Cloudflare receives an empty, unknown, or malformed response from the origin.
How to Fix
Check origin server logs. Ensure responses include proper headers. Verify SSL configuration.
Description
Cloudflare-specific. A TCP connection was established but the origin didn't respond with an HTTP response in time.
When You See It
When a request to the origin takes longer than Cloudflare's 100-second timeout.
How to Fix
Optimize slow endpoints. Move long-running tasks to background jobs.
Key Differences
HTTP 520: Cloudflare-specific. The origin server returned an unexpected response that Cloudflare could not process.
HTTP 524: Cloudflare-specific. A TCP connection was established but the origin didn't respond with an HTTP response in time.
You encounter 520 when when Cloudflare receives an empty, unknown, or malformed response from the origin.
You encounter 524 when when a request to the origin takes longer than Cloudflare's 100-second timeout.
When to Use Which
For 520 (Web Server Returned an Unknown Error): Check origin server logs. Ensure responses include proper headers. Verify SSL configuration. For 524 (A Timeout Occurred): Optimize slow endpoints. Move long-running tasks to background jobs.