VMware yesterday released the update to vCenter 5.1 Update 1 a which replaces the previous update which contained a problem with the Single Sign On service.
vCenter Server 5.1 Update 1 has been removed from the VMware download site due to issues encountered when logging in to vCenter Server 5.1 Update 1 with domain credentials.
The complete release notes can be found here.
New After upgrading to vCenter Server 5.1 Update 1, attempts to log in to vCenter Server might fail if the vSphere set up has large numbers of domain groups
Coincidentally I ran in exact this issue just 2 days ago when I was upgrading a customer from vSphere 5.0 to 5.1 U1. I updated my existing post about SSO which can be found here.
One issue which I faced yesterday, was a phenomena that the login for the same user sometimes was possible and sometimes was not!
So for example if I used the “Use Windows session credentials” option the login worked mostly (this option uses an existing kerberos ticket). But when we tried the exact same user for example in the customers monitoring solution, access was denied (requests new ticket). But now, because it isn’t annoying enough, sometimes lets say 1 out of 10 attempts the behavior was reversed. We asked the VMware support guys who were kinda surprised and we decided to wait for 5.1 U1 a. I will update this post as soon as I know if this problem is related to the one fixed in the update.
I already got feedback from co-workers as well as customers who reported that this update fixed their problems! So if you face issues logging in to your vCenter, you should go ahead and update your vCenter, in particular the SSO service.