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Main reasons for 520,521,522 cloudflare errors

2019-02-21

520 HTTP STATUS RESPONSE – CLOUDFLARE ERROR

Cloudflare servers return this code. As you may know, when a website uses Cloudflare, a proxy server lies between the client and the web server. When a 520 error occurs, it means that the said proxy server at Cloudflare received an unexpected response from the web server.

REASONS FOR A 520 ERROR


• Connection resets after a successful TCP handshake
• Headers that exceed Cloudflare’s header size limit (8kb)
• An empty response from the origin server
• An invalid HTTP response
• An HTTP response without response headers
This is likely a settings problem from the web server.


521 HTTP STATUS RESPONSE – CLOUDFLARE ERROR


This HTTP status is only returned by Cloudflare servers. It occurs when the web server does not answer. It
would likely end up in a “timeout” without a Cloudflare server in the middle.


REASONS FOR A 521 ERROR


• A firewall prevents Cloudflare servers to access the web server. The firewall sends a packet in return to tell the client that it refuses the connection.
• A program sends back a “connection refused” message to the client.


522 HTTP STATUS RESPONSE – CLOUDFLARE ERROR


This HTTP status is only returned by Cloudflare servers. It occurs when the web server does not answer. It would likely end up in a “timeout” without a Cloudflare server in the middle.


REASONS FOR A 522 ERROR


• A firewall prevents Cloudflare servers to access the web server. The firewall drops packets from a Cloudflare server.
• The web server service is stopped on the web server
• A program blocks any response to Cloudflare requests

Related Posts:

  • Disadvantages and Advantages of using CloudFlare
  • Can switching your website to HTTP/2 be a problem for google indexing?
  • The HTTP date headers exchange when retrieving a web page
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