Some time web client start but , facing the issue for login and got the error 503.  Mostly issue in 6.0 U2 which is resolved in U3

 

  1. 1. Temporary  solution :- Increase MaxPermMB size 

 

https://kb.vmware.com/s/article/2148445

  1. 2. Permanent: - Upgrade your infrastructure according to 6.0 U3.

 

          https://kb.vmware.com/s/article/2148355