In our lab infrastructure we have two or three little ESXi hosts managed by a vCenter Appliance. A few days ago, suddenly root login was not possible anymore. Most of the other local accounts worked, however.
My first thought was that someone changed the password and forgot to document that, however, no one lifted his fingers…
The 5.5 release of the vCenter Server Appliance (vCSA) enforces local account password expiration after 90 days by default. This policy locks out the root account when the password expiration date is reached.
Okay… thanks for the explanation. I then did a password recovery and disabled this great new feature, now we can work again (both explained in the KB article)