I can't lie... I am a bit apprehensive to install this until I see the forum is ok with patching.  The last patch 4 months ago broke our environment.  The Hotfix DID fix it but it was a major issue and had to work over the weekend to get it back up and running. 

Is anyone else reporting issue from installing upgrade 15.3.1?  Thank you in advance.

Is this reported to support yet?

I saw this but only in for one certificate, everything else was fine. We ended up reissuing the certificate from a different provider and it was fine. Not sure what would cause that but maybe 15.3.1 doesnt support some specific certs?

ivodlouhy do you know if a change to OpenSSL in 15.3.1 may be the reason for this error with specific certs?

That is normally an issue between the server and client where they do not have matching ciphers / SSL or TLS verisons. You may need to enable older or newer SSL/TLS versions in your browser. If the site is public facing the you could use https://www.ssllabs.com/ssltest/ to check the SSL/TLS versions supported and what ciphers are in use.

Thanks tjones2019, yes I did that exact check and SSL Labs simply said it could not connect. Think by default TLS1.1 is no longer supported in 15.3.1 so I wonder if certain certificates if they are old dont have capability to work with TLS1.2 or 1.3, seems odd but thats the only explanation I could think of?

Odd, not seen certificates tied to TLS versions. I wonder if duing the upgrade it lost the private key to the certificate? Not used the Serv-U software so just guessing. When you got it re-issued did you generate a new CSR from the server and send this to the supplier?

It was from a new CSR, so maybe it's the old private key format that was not supported?

Has anyone reported this to support?  I really do not want to go through what we did with the last upgrade with our Serv-U instance being behind a load balancer..

Could someone from support comment on this?  Is anyone else experiencing issues after installing the hotfix?

Thank you all in advance,

I doubt Support are here much, what this with HotFix? We are talking about full release 5.3.1 here not 5.3.0 plus HF1.