I had been troubleshooting a failed vCenter upgrade recently and trying to restart the upgrade process. Every time I would run the installer, it would fail on some piece and rollback the install. I had opened up several windows trying to figure this out, including Event Viewer, Services.msc, log files, etc. and wasn’t easily able to find a reason for the failures. At one point, the error that I was getting was something about permissions denied; which was strange, as the account I was using had full admin rights on the system and SQL server.
I found an obscure posting on some forum somewhere that suggested closing down the services.msc window and then running the install again. I did so and the install was successful! I’ve never seen an application that had to have the Services.msc window closed in order to add or remove services, but some portion of this install process seemed to require it.