Error 526 Invalid Certificate on a domain + server + valid cert

Website, Application, Performance Security
1

What is the name of the domain?

https://ciurana.eu

What is the error number?

526

What is the error message?

Invalid Certificate

What is the issue you’re encountering

The server was wowrking fine until about 2 hours ago, then this error cropped up. The cert is valid.

What steps have you taken to resolve the issue?

  1. Checked the certificate validity
  2. Checked the web server configuration
  3. Checked other web servers with SSL certs on the same IP/box - they work fine

From our point of view, everything is working as expected but we have no idea why Cloudflare rejects the certificate now after working without problems since it was issued, last November.

Thanks in advance!

What is the current SSL/TLS setting?

Off

2

Can you change the DNS record to DNS-Only for a moment so I can verify that?

3

Give me a sec - I modified SSL from Full to none back to Full in another domain that points to the same box (ciurana.ru) and it responds again fine. Please stand by.

4

It works now, after flip flopping the SSL encryption mode Full/None/Full.

Another service on the same box + Cloudflare, pypi.cime.dev and also using a Let’s Encrypt cert was unaffected. Only the ciurana.eu and ciurana.ru domains seemed to have the issue.

I wonder if this had to do with the automatic encryption mode roll-out from Cloudflare.

Thanks for your help, have a great weekend.

5

Full ignores ANY problems with the certificate and is thus unsafe.

If you change your DNS record to DNS-Only for a moment, it’s very likely we would see an expired certificate.

6

One more, eugeneciurana.com was affected, flip/flop, back to normal. Weird. Have a great weekend!

7

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