I recently setup a new server running plesk. I secured the domain using Plesk’s letencrypt extension.
When I tried to access the domain I received the following error:
“Error 526 - Invalid SSL Certificate”
When I changed the crypto from Full (Strict) to Full it works fine.
So it appears Cloudflare has an issue with the certificate.
Plesk’s support article, simply states it’s related to a misconfiguration in cloudflare:
How to continue to troubleshoot / rectify so Full Strict, does not generate any errors?