Solution to stop Cloudflare 520 errors

[wwillson]

When we turned off Cloudflare "Speed=>Optimization=>HTTP/2 to Origin", the 520 errors completely went away and we haven't seen a single 520 since.

 

[rdn]

All the websites I managed use the CloudFlare to Origin (HTTP2) option, but no problem at all; maybe your backend implementation of HTTP2 is somewhat broken?
I guess it's based on LiteSpeed or OpenLitespeed (they seem to produce very edgy, unstable versions of HTTP2 and Quic)?

Mine are all based on Nginx.

 

[digitalpoint]

I've never had an issue with HTTP/2 to origin either (also using Nginx for my stuff). If you are using an old version of Nginx, probably not a bad idea to upgrade it. If you are using something other than Nginx at your origin, might not be a bad test to try Nginx just as a test to see if whatever is going on is unique to your web server.

 

[MySiteGuy]

Since I stumbled upon this myself, I've seen issue happen on Nginx as well. I have many clients using OpenLitespeed and some using Litespeed Enterprise since I offer Cyberpanel based setup, and have not found this to be a problem.

There many people experiencing this with Nginx + Cloudflare. If you search, you'll find far more hits for this problem with Nginx than Litespeend and Apache combined.

520 nginx cloudflare http2 - Google Search

To me, it seems to point to Cloudflare being the problem, because it happens with Nginx, Litespeed and Apache in various degrees. I haven't done enough investigation to know for certain what the circumstances are causing it. Disabling origin HTTP2 solves it at least for now, so I'm not going to burn up costly time on it.

 

[wwillson]

Huge thanks to @MySiteGuy for helping us figure this out!

 

[drastic]

Just posted about this same issue.

This thread solved it for me!