Earlier today, Microsoft released this security advisory:
Microsoft Security Advisory: Update for minimum certificate key length
After applying the Microsoft Security Advisory:
- Connections to secure http (https://) web services such as the Managed Object Browser (https://vcserver/mob) and to WebAccess (https://<vcserver>/ui) fail if the vCenter Server certificate is 512 bit
- Redirection of communication from http to https fails and communication proceeds over the http connection
The patch effectively disables communication with any security certificate which is less than 1024 bits long. With vCenter 4.0.x we use 512 bit certificates by default and as such we see connections to https Web Services fail.
For further information, updates, and resolution to this issue, refer to KB article: After installation of Microsoft Security Advisory update (KB2661254), connection to vCenter Server 4.0.x web services may fail (2037082).