I just update my Vcenter from 5.0 to 5.1. In version 5.0 I had installed SSL certificates properly, after update I'm able to add certificate on Vcenter 5.1 back on server but if I reset the server the VCenter server didn't start.
There is any additional step to perform when I added the certificate on Vcenter 5.1?
Did you follow this KB to replace the certs?
Don't make your life harder than it needs to be
Instead of going the manual way you can use the SSL Automation Tool.
Deploying and using the SSL Certificate Automation Tool