520 - again and again

Hi,

I’ve asked the same question already but have not recevied any answer other than “the origin disconnects”.
We are experiencing 520 error. It happens few times per hour. We checked everything we could, we have also changed our server for the new one with more performance. We have excluded the possibility that our server is responsible for that as we tried to reach it directly (without cloudflare) and no 5xx error was registered. We also generated huge number of requests directly to our server and did not experience any 5xx error.
When we connect via Cloudflare we got the 520 for a few times per hour.

None of Cloudflare IPs is blocked on firewall. Our VPS provider does not block anything. Our server is loaded for 20% of its performance most of the time. But 520 still happens.

The last time we experienced the 520 the Ray ID on request was 633937219a432c76.

How to resolve this issue?!

Due to 520 error and the more detailed explanation here:

Have you checked with the steps as written on the below article?:

What is your domain name?
Is the domain pointed to Cloudflare nameservers?

Have you checked your web server log files and firewall?

Do you use any other CDN with Cloudflare?
Do you use any CMS like WordPress?
Do you already have an SSL certificate installed at your origin/host for your Website(s)
(domains and sub-domains)?
Have you got CNAME or A records for your domains pointed to your origin/host IP address at Cloudflare dashboard?

Do you use Microsoft or Linux OS?
Does the client at your origin support SNI for client connections?

Who is the hosting provider?

Are the needed one and compatible ports with Cloudflare openned at the Origin/Host/Server and apps running on them (and not on the incompatible ones)?

Is Cloudflare allowed to connect to your origin/host?

Have you tried writing a ticket to Cloudflare support?

https://dash.cloudflare.com/redirect?account=support

1 Like

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

Is your website overloaded? Are cloudflare IP’s set to “allow” or “bypass”? I’d recommend allowing or allowing these IP’S to bypass
173.245.48.0/20
103.21.244.0/22
103.22.200.0/22
103.31.4.0/22
141.101.64.0/18
108.162.192.0/18
190.93.240.0/20
188.114.96.0/20
197.234.240.0/22
198.41.128.0/17
162.158.0.0/15
104.16.0.0/12
172.64.0.0/13
131.0.72.0/22
2400:cb00::/32
2606:4700::/32
2803:f800::/32
2405:b500::/32
2405:8100::/32
2a06:98c0::/29
2c0f:f248::/32

If that doesn’t help give me the website URL

Hope to hear back, thanks!

This topic was automatically closed 5 days after the last reply. New replies are no longer allowed.