We have upgraded vcenter 5.5 to 6.0 after upgrade joined the AD from Web client it is working fine if we put credentials manually but when we select “Use Windows Session Credentials ” it gave below error msg using #client .

In Our case it was due to AD.
From webclient vcenter didn’t join to AD properly so we had to use command line to re-join to domain.
Enable SSH and Bash Shell of vCenter appliance
Run below command to check if server is in AD or not.
vcenter:~ # /opt/likewise/bin/domainjoin-cli query
Now Run below command to join vcenter to Domain :
vcenter :~ # /opt/likewise/bin/domainjoin-cli join yourdomain.com username
Joining to AD Domain: yourdomain.com
With Computer DNS Name: vcenter fqdn
Username@domain password:
SUCCESS
vcenter:~ # reboot
Now we can access the server with “Use Windows Session Credentials “