It's a Vcenter on a Windows server 2008 R2.
With 5.1 vcenter.
And the SSO server is on another server.
Have you tried restarting both SSO and vCenter?
Are SSO services up and running on the SSO machine?
Yes i restarting both SSO and vcenter.
I found a strange things in Administraion of SSO , the application users of the vcenter have been deleted.
I can't reconfigure the vcenter for recreate a new application users becaus my vcenter don't want to restart. Do you have an idea?
Finaly, i uninstall/reinstall the vcenter. In the install process, he offered to re-register the vcenter in the SSO.
All is ok now.