I initially upgraded vCenter 5.5 to 5.5 update 3 and no issue. When I tried to then patch a host, (stage worked), remediate gave me an error:
Remediate entity idcesx06.parkernet.edu VMware vSphere Update Manager had an unknown error. Check the events and log files for details.
I've checked through logs and am not seeing anything helpful.
I gave up after a while and decided to try and upgrade/migrate from windows vcenter 5.5 to vcsa 6.5, when I run the Migration Assistant and it does its pre-check, it fails with "Error: vCenter CA certificate not verified. Stopping. Resolution: Please use the vCenter Upgrade Logs to get more details of this error.".
I am wondering if both issues then are related to a certificate issue? Is that vcenter or Windows box?