I ran into this error when upgrading one of our hosts to ESXi 5.0 from 4.1u1 via format and re-install. Everything joined back normally, I was able to vMotion machines back onto the new host, etc.; however, once I tried to open the console I was greeted with: Unable to connect to the MKS: The remote host certificate has these problems: *unable to get local issuer certificate * Host name does not match the DNS name in certificate.

After some tinkering (and googling to no avail), my solution was to reboot the host, remove the host from vCenter, and then re-add the host back. I believe the issue was compounded by a couple of unique issues, but I’ll spare the boring details on reproducing. Simple fix, but since I wasn’t able to find a solution when googling the error message, I figured it would be worth tossing this blog post up to hopefully expedite someone else’s troubleshooting.

Update (8/23/12): A reader sent me an email saying they ran into the issue due to the following as well: “In my case in turned out to be a local hosts file had an entry for one of the esxi hosts that was pointing at the wrong IP.”