Starting to get an error for no reason: 5xx :(

For no reason, I started getting the following errors. The errors, which started around 00:58 tonight, are as follows. However, there is one thing: when I activate dev mode, the problems go away and there are no problems left. What do you think I should do?

These errors show Cloudflare cannot reach your origin server. Development mode bypasses the cache.

Check your origin server is still up and working, is on the same IP address as you have set in your Cloudflare DNS and isn’t blocking requests from Cloudflare’s IP addresses.

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A 5xx error occurs when there is an issue communicating with your origin server.

Error 523: origin is unreachable

Error 523 occurs when Cloudflare cannot contact your origin web server. This typically occurs when a network device between Cloudflare and the origin web server doesn’t have a route to the origin’s IP address.

Error 524: a timeout occurred

Error 524 indicates that Cloudflare successfully connected to the origin web server, but the origin did not provide an HTTP response before the default 100 second connection timed out.

CJ313

Hello,

For no reason, I started getting the following errors. The errors, which started around 00:58 tonight, are as follows. However, there is one thing: when I activate dev mode, the problems go away and there are no problems left. What do you think I should do?

As we see for both of these errors we are indicating that we are unable to connect to your origin code due to these errors. By disabling the proxy you are bypassing us so we are not able to generate these errors that we see when we cannot connect to your origin. These are all origin related errors. See documentation below.

Error 523: origin is unreachable

Error 523 occurs when Cloudflare cannot contact your origin web server. This typically occurs when a network device between Cloudflare and the origin web server doesn’t have a route to the origin’s IP address.

Resolution Contact your hosting provider to exclude the following common causes at your origin web server:

  • Confirm the correct origin IP address is listed for A or AAAA records within your Cloudflare DNS app.
  • Troubleshoot Internet routing issues between your origin and Cloudflare, or with the origin itself.

If none of the above leads to a resolution, request the following information from your hosting provider or site administrator:

  • An MTR or traceroute from your origin web server to a Cloudflare IP address that most commonly connected to your origin web server before the issue occurred. Identify a connecting Cloudflare IP from the logs of the origin web server.

Error 524: a timeout occurred

Error 524 indicates that Cloudflare successfully connected to the origin web server, but the origin did not provide an HTTP response before the default 100 second connection timed out. This can happen if the origin server is taking too long because it has too much work to do - e.g. a large data query, or because the server is struggling for resources and cannot return any data in time.

A 524 occurs if the origin web server acknowledges (ACK) the resource request after the connection has been established, but does not send a timely response.

Resolution

Here are the options we’d suggest to work around this issue:

  • Implement status polling of large HTTP processes to avoid hitting this error.
  • Contact your hosting provider to exclude the following common causes at your origin web server:
    • A long-running process on the origin web server.
    • An overloaded origin web server.

Logging request response time at your origin web server helps identify the cause of resource slowness. Contact your hosting provider or site administrator for assistance in adjusting log formats or search for related logging documentation for your brand of web server such as ApacheOpen external link or NginxOpen external link.

  • Enterprise customers can increase the 524 timeout up to 6000 seconds using the proxy_read_timeout API endpointOpen API docs link. If your content can be cached, you may also choose to use a Cache Rule with the Proxy Read Timeout setting selected instead in the Cloudflare Dashboard.
  • If you regularly run HTTP requests that take over 100 seconds to complete (for example large data exports), move those processes behind a subdomain not proxied (grey clouded) in the Cloudflare DNS app.

Please note that you may observe a 1 second difference between the timeout you’ve set and the actual time at which the Error 524 is returned. This is expect, it’s due to the current work on implementing Pingora, our new proxyOpen external link. As a workaround you can simply set the timeout to 1 second more (121 seconds instead of 120 seconds for example).

These items above should lead to resolution of these errors. At that time frame I would also observe your origins access log to see what may have been happening to your zone. As we see both of these errors showing an origin error that is very little we can do to troubleshoot this as your origin is returning this response to us.

CJT313

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