HTTP 422 Unprocessable Content vs 520 Web Server Returned an Unknown Error
HTTP 422 (Unprocessable Content) is a 4xx Client Error response, while 520 (Web Server Returned an Unknown Error) is a 5xx Server Error response. 422 indicates that the server understands the content type and syntax, but was unable to process the contained instructions. Common in API validation errors. In contrast, 520 means that cloudflare-specific. The origin server returned an unexpected response that Cloudflare could not process.
Description
The server understands the content type and syntax, but was unable to process the contained instructions. Common in API validation errors.
When You See It
When form validation fails — correct syntax but invalid data (e.g., email format wrong, date in the past).
How to Fix
Check the response body for specific validation errors and correct the input data.
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.
Key Differences
422 is a 4xx Client Error response, while 520 is a 5xx Server Error response.
HTTP 422: The server understands the content type and syntax, but was unable to process the contained instructions. Common in API validation errors.
HTTP 520: Cloudflare-specific. The origin server returned an unexpected response that Cloudflare could not process.
You encounter 422 when when form validation fails — correct syntax but invalid data (e.g., email format wrong, date in the past).
You encounter 520 when when Cloudflare receives an empty, unknown, or malformed response from the origin.
When to Use Which
For 422 (Unprocessable Content): Check the response body for specific validation errors and correct the input data. For 520 (Web Server Returned an Unknown Error): Check origin server logs. Ensure responses include proper headers. Verify SSL configuration.