Sometimes a CF 520 error

Awesome to hear you guys found it! Thank you for your support!

Hi. I have the same problem since I enabled CF. Ticket # 2227760

Ticket #2227054

Same issue here, was doing numerous tests since most 520 searches say “it’s server side”

Good to hear that it’s not because I could not find ANYTHING and had the issue across two separate servers and multiple sites.

I wanted to make a HAR dump today, but I noticed that the error no longer returns.
Would the annoying 520 error finally be solved? :smiley:

The status page does report this as resolved, yes

I’m glad to hear you’re no longer having issues.

If anyone is still getting a 520, it is unlikely to be related and may be a server-side issue. You might want to check Community Tip - Fixing Error 520: Web server is returning an unknown error and open a new topic if you are still having issues.


Thank you. I’m just interested: Is there also known what exactly went wrong at CloudFlare? :wink:

1 Like

Yup, seems to be fixed.

My testing the other day which almost consistently would get it to 520 has gotten zero 520s across various sites I retested.

Taking a quick look, I still got a 520 error (1), but apparently it’s gone down a lot.

Here the error continues :slightly_frowning_face:

It didn’t return the error 520 anymore!

Error 520 still occurs, but much less frequently than before.

I haven’t seen a 520 since yesterday. The 520 error rate per last 24h is down from around 0.4% to 0.1%, but full 24 hours have not passed yet since the fix was implemented.

Not solved. I saw another 520 error just a few minutes ago.

520 errors decreased but sometimes they still appear (tested with locust around 10 users simulation)

Nice to see CloudFlare recognize there was indeed an issue. Their Incident Report shows this is resolved, however it’s still happening across our websites.

Kindly requesting Cloudflare look deeper into this issue. Looking at this thread, it’s clear many people are experiencing this same issue.

I have done a very deep dive at server logs at the system level, domain level, and user level… and nothing. No errors are shown, yet Cloudflare 520 errors continue to happen… again, completely random and never a pattern. Works great for 10 clicks through, 1 error, 50 clicks through, then another error. Frustrating.

I have disabled the CSF Firewall on the server. I have disabled Mod Security. Tried different browsers. And still get the CF 520 errors.

Everything was working great for years, literally years… and all of a sudden, out of the blue, CF 520 errors.

Please Cloudflare, help us!

Seems like the 520s regrouped and struck again. I had a 520-free day yesterday but starting this morning they are back again in exactly the same way they had been for two weeks before yesterday. The rate of 520 errors first went down from 0.4% to almost zero by this morning but now it’s back to 0.25% and growing. Was the fix rolled back somehow?

Please submit a ticket and post the ticket number here and we’ll investigate further.

1 Like

My ticket number: 2231106

1 Like

I turned CF back on and the 520 errors came back. I took the Trace ID’s and the CDN-CGI Trace info, for multiple websites across servers completely independent of each other, and that info was submitted.

Cloudflare Support Ticket Number 2231567

Thank you for your help. I appreciate it.