Error 520 in Joomla admin

In the backend of Joomla I often get an error 520 from Cloudflare. In the error log I found this:

[Thu Sep 02 16:52:03.641211 2021] [lsapi:error] [pid 3870398:tid 139661802080000] [client 172.69.62.80:11274] [host zoo-educatie.nl] Error on sending request(GET /?Itemid=2179 HTTP/2.0); uri(/?Itemid=2179) content-length(0): ReceiveAckHdr: nothing to read from backend (LVE ID 1384), check http://docs.cloudlinux.com/mod_lsapi_troubleshooting.html

Does anybody know How I can solve this?

Error 520: web server returns an unknown error

Error 520 occurs when the origin server returns an empty, unknown, or unexpected response to Cloudflare.

Resolution

A quick workaround while further investigating 520 errors is to either grey cloud the DNS record in the Cloudflare DNS app or temporarily pause Cloudflare.

Contact your hosting provider or site administrator and request a review of your origin web server error logs for crashes and to check for these common causes:

  • Origin web server application crashes
  • Cloudflare IPs not allowed at your origin
  • Headers exceeding 16 KB (typically due to too many cookies)
  • An empty response from the origin web server that lacks an HTTP status code or response body
  • Missing response headers or origin web server not returning proper HTTP error responses

520 errors are prevalent with certain PHP applications that crash the origin web server.

If 520 errors continue after contacting your hosting provider or site administrator, provide the following information to Cloudflare Support:

Thank you for your reply.
I paused Cloudflare and since then the error did not occur any more.
So probably it is caused by Cloudflare?

I don’t know but what is the domain? (I might be able to see if the error occurs on my end right now)

You may want to contact cloudflare support (but that’s up to you)

The domain is: zoo-educatie.nl (this is my testserver)

The live server with the same problem is zoo-info.nl (for this domain I did not pause Cloudflare).

The error only occurs in the backend, mostly when I delete the cache in Joomla, or delete all records of a table.

Wait so it’s only occurring in a specific area?

That is correct, only in the backend of Joomla

This is a line in the error log:
[Thu Sep 02 16:52:03.641211 2021] [lsapi:error] [pid 3870398:tid 139661802080000] [client 172.69.62.80:11274] [host zoo-educatie.nl] Error on sending request(GET /?Itemid=2179 HTTP/2.0); uri(/?Itemid=2179) content-length(0): ReceiveAckHdr: nothing to read from backend (LVE ID 1384), check http://docs.cloudlinux.com/mod_lsapi_troubleshooting.html

So it’s a failed API request (API request failed)?

I don’t think it is an API request. It’s in the standard admin part of Joomla. It is just deleting cache and deleting records. I don’t think that has anything to do with an API request?

What do you mean? Is it not reading the cache?

What I mean is that I empty the cache in the admin part of Joomla to see the effect of changes.
Or I just delete records from a table in Joomla

Try clearing the cache first, if that doesn’t work then try deleting the records

Do you get the error immediately, or does it take a minute or so before it errors out?

Deleting the cache or deleting records is not the problem, the problem is that after that I get an error 520. When I refresh the screen, the error is gone. But it is annoying that I see that error 520 every time.

How exactly can I imagine your setup? Do you have Cloudflare connect directly to your server or are there any additional proxies, of yours, in-between Cloudflare and your actual origin?

The website is hosted by a service provider and connected directly to Cloudflare. I don’t have any proxy installed. But I don’t know or the provider uses any proxy.
I also asked them to have a look at the problem.

Could you try temporarily disabling HTTP 2 on your server? I’d be curious if that might just fix it.

Which error log did you find this error message from? I’m having similar issue with intermittent 520 errors in both joomla frontend and backend.