Error 521 page is being experienced recently

we have started receiving 521 errors today.

the problem occurs across multiple servers hosted across different data centres.

we haven’t changed any settings in Cloudflare for months and to start receiving 521 errors seems strange to me that two separate data centres with different domains running on the servers are having the same issue.

the issue is intermediate and goes away after the user refreshes the browser. Any advice on this would be helpful please.

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after posting this ticket i was browsing the web on a totally separate website which we do not manage or own and i experienced the same problem that our customers are experiencing with our websites.

surely there must be a problem with cloudflare right?

I also experiencing this problem today. The error 521 show intermittently to my websites hosted in different data center.

how do we get cloudflare to investigate as i am starting to plan moving back to AWS Route 53 if this is going to continue for long. clients dont understand that is not something we can support

We are also experiencing this too. This is annoying.

I don’t think Cloudflare will act on free plan though.

however i am certain its occuring across all the plans for cloudflare. we are a business customer

i have raised a ticket with cloudflare support just now as a business customer i hope they attend to it asap since the problem seems to be getting worse

me too, what happen? I disable Cloudflare and the website back to normal

If should be the problem between Cloudflare to the origin server, that’s why you disable the DNS proxies, I back to normal.

Same problem, with Cloudflare, around 5% of all non-cached requests immediately return 521 error to client recently.

Without cloudflare, it is working fine.
Furthermore, cached request is working find too.

I am using DigitalOcean (Singapore).

I tested different cloudflare nodes in NRT, SIN, LAX (Japan, Singapore and US)

My simple test result:
statusCode: 521
“Wed, 10 Feb 2021 03:58:58 GMT”



statusCode: 521
“Wed, 10 Feb 2021 03:59:36 GMT”

statusCode: 521
“Wed, 10 Feb 2021 03:59:41 GMT”

Last 24 hours 5xx error:

same problems here across multiple domains , this need to be fixed asap .

Issues here also… Please fix asap!

Happening frequently to our websites and also partners’ websites, please fix the problem ASAP!

Noticed this too today from 9am AEDT (GMT+11)… not only our site but others that also use Cloudflare - not application-specific (seen this on Wordpress, Magento etc…) - random requests (1 in 20 to 1 in 40) receive 521 immediately, next refresh works as usual
We’re a business customer and have lodged a ticket with Cloudflare support via our hosting partner who’s a Cloudflare wholesaler with many clients to they may have a higher priority in the ticket queue

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I was about to upgrade to Pro Plan and I thought it would solve the 521 problem, but I think it doesn’t help at all since reading reports that business users also experiencing the same problem

My first e-mail alert was on 0:17am GMT on my websites. Refresh does help, but still affect customer experience. Hope there are more business and enterprise users report to CF. As I don’t see any outage in Cloudflare status yet.

Trying this on a test site of mine behind CF. Can confirm that 2-3 out of 40 requests made per second will return a 521. A packet capture running on the origin server shows that no packets are received when the 521 is returned by the CF Ray.

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I have 10 sites piped through cloudflare and all of them have 521 problems.

I’ve received several “[Cloudflare]: Server Unreachable [Error 521: Web server is down]” notification emails for various sites over the last 24 hours. I’m guessing this is related to the above issue. My sites/servers are all fine. Something’s definitely up at CF.