Community Tip - Fixing 5XX Errors & All 5XX Tips

Introduction
Use this Community Tip to understand more about 5XX errors, identify if they are from the origin server or the proxy, and click-through to supporting Community Tips for troubleshooting.

Background
Generally, 5xx error codes indicate that an error or unresolvable request occurred on the server side, whether that is a proxy or the origin host. The server was able to detect the error and thus will not return the potentially malformed response to the client. These error codes be used as a response to any request method and fall into two categories, 5xx errors from your host and other 5xx errors that Cloudflare generates when errors contacting the origin are encountered. This tip addresses both types of 5xx errors.

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Origin 5xx Errors
When the origin server sends an error, it should include an explanation, which should be displayed by User-Agent, with the exception of a HEAD request. The following errors are typically returned by the origin web server.

500 Internal Server Error
501 Not Implemented
502 / 504 Bad gateway / Gateway Timeout
503 Service Unavailable
505 HTTP Version Not Supported
508 Resource Limit Is Reached

Other 5xx Errors
520 unknown error
521 Web server is down
Email alert, origin unreachable
522 Connection timed out
523 Origin is Unreachable
524 A Timeout Error
525 SSL handshake failed
526 Invalid SSL certificate
527 Railgun Listener to Origin Error
530 Origin DNS Error

Third-Party Troubleshooting Suggestions
Answered on :q:

If You Need More Help
This community of other Cloudflare users may be able to assist you, login to Cloudflare and post your question to the Community. When you post on the Community make sure to include as much of this information as possible: the specific error message you are seeing, the URLs this is happening on, screen shot of the error, and the steps to reproduce the error. Please indicate what troubleshooting steps you’ve tried in order to help us help you.

This is a Cloudflare Community Tip, to review other tips, click here.

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