Sometimes a CF 520 error

Pinging @MoreHelp - any chance of an update on this? I’m still seeing ~1% 520 errors, and as mentioned in my previous post I don’t get any errors at all if I bypass Cloudflare. Example error ray ID: 6817189d0b1b2eb6-SIN. Looks like many people are experiencing this same problem.

Good night, I removed the CF yesterday, and today I didn’t have any 520 errors. Chris last answered me 7 days ago, I sent the HAR he asked for and then he didn’t answer me anymore. Unfortunately it’s a CF bug, and either they don’t want to fix it because it’s in the free zone, or they haven’t put anyone in to investigate it for real. The easiest solution at the moment is to remove the CF

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Chris M. (Cloudflare)

Aug 12, 2021, 9:52 AM PDT

Hello,

We are seeing that the origin server is rejecting HTTP/2 connection attempts. As a workaround, are you able to disable HTTP/2 on the origin server? To get more insight into the error on the server, we’d suggest increasing logging verbosity and looking for errors around HTTP/2 protocol errors if possible. Our logs are simply showing that the origin is rejecting these requests.

Chris M.
Technical Support Engineer | Cloudflare
Search the Cloudflare Community for advice and insight.

Chris M. (Cloudflare)

Aug 12, 2021, 3:41 PM PDT

Hello,

If you are able to replicate, could you send us a HAR file that captures the error?

How to generate a HAR file.

That will help us to look up the error in our logs further and help us replicate as well.

I would also suggest contacting your hosting provider and ask them to check the server logs for errors around these connection attempts to see if there are any errors logged there as well.

Chris M.
Technical Support Engineer Cloudflare
Search the Cloudflare Community for advice and insight.

Hey everyone, a few weeks ago I saw a big increase of 520 errors as well. I’ve been checking the Error Analytics consistently and it has never been more than 150-200 requests in 24 hours, now it’s about 1500 errors every day.

My ticket number is: 2218491

Hope Cloudflare takes this seriously, as it’s clearly a problem on their end, and it all seems to have started in the past month or so. Hopefully, I won’t have to switch to another CDN, but I will have to if this isn’t addressed.

Same for me has had this problem since end of july,
Betweeen 3 aug and 16 aug just a few errors a day and from 19 aug many errors again.

I want to cry because this problem is happening on multiple websites spread across multiple servers, independent of one another.

What makes this more believable is there were absolutely zero problems for many years; Cloudflare worked great. And then around the week of July 22, something (I don’t know what) changed and it’s been 520 errors ever since.

Please help find resolve to this issue. Frustrated.

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May I ask which hosting providers or any “in between” like Google Fiber ISP for customers?

We are having the same issue with our sites. Ticket #2237325

Disabling Cloudflare completely resolves any errors. Just getting very random 520 errors and the response time is so fast that I don’t think it is even possible Cloudflare reached the origin server (Bangkok to NYC and back in under 200ms) so that tells me it is on Cloudflare’s end

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The CF Ray from one of the 520 responses: 6831480a983e26cd-BKK

Got the same problem here. 522 errors while tring to open site in browser. My ticket is 2237414 about this issue, but i got automated answer and got here.

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Hey Max, just a heads up in case you misread the thread title - this thread is about 520 errors. As far as I can see no one else in this thread is reporting 522 errors alongside their 520 errors. So although it’s possible your issue is related, it’s likely that it’s something else.

Maybe the 520 error occurred 522 times, lol.
I gave up on CF.

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Is CF still thinking it is a clientside problem, or is it perhaps a little bit escalated already?

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Hello, I have the same error 520, somestimes it work and sometimes doesnt

@MoreHelp

Can someone at Cloudflare please assist us?

I’m having random 520 errors here as well across multiple servers, multiple domains and multiple devices/internet connections in different parts of Canada. It has been going since at least the beginning of August 2021, possibly before that.

When I see the error, I don’t see any requests on our servers so it doesn’t seem like CF is passing the request through (even when not cached). Almost always, refreshing the page loads the page immediately. Grey clouding it results in everything working without issue.

@MoreHelp The same issue in Russia. Ticket #2237489

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We are seeing that xxxxxxxxxx has been removed from Cloudflare at this time. Our internal investigation determined the Always Online feature was causing issues or other issues at the origin server.

If you continue to experience issues, please increase the logging level at the origin

A 520 error happens when your origin returns a response that is unexpected.

There are two key instances where this can happen in my experience:

  • Your web server or networking equipment (Firewall, Load Balancer) reset the TCP connection after it was established. Sometimes when a web server crashes it will reset the connection. Check your web server access/error logs for the timescale that the error occurred in and look for any error messages.
  • Your web server returned an invalid response that exceeded our limits. Often this can happen if your web server is returning too many/too large headers. This is often caused by runaway scripts that return too many cookies, for example. The Code Igniter PHP framework has some known bugs around this too.

Chris M.
Technical Support Engineer | Cloudflare
Search the Cloudflare Community for advice and insight.

We have just received an update that the continued 520s do not look like a Cloudflare issue, as there was before. This thread was related to Cloudflare Status - Elevated 520 errors on Free Zones. That issue is now resolved.

If you are still receiving 520s, they are likely caused by an issue on your origin server. Please follow the guidance in the #CommunityTip and Support Center.

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