Following error can be seen in /var/log/xdl/vda.log when a Linux VDA tries to start

 

2016-07-01 20:12:30.858 [ERROR] - DbPreferences.GetKeyID: Failed to get KeyID. Error: Connection refused. Check that the hostname and port are correct and that the postmaster is accepting TCP/IP connections.
2016-07-01 20:12:30.865 [WARN ] - The Citrix Desktop Service failed to connect to the Citrix Configuration Database.
Please ensure the Citrix Configuration Database Service is running before starting the Citrix Desktop Service.
The service will retry connecting to the Citrix Configuration Database in approximately 15 seconds. Retry attempt: 1.
Error details:
Exception 'LOCAL registry could not be initialized.' of type 'RegistryNotFoundException'
2016-07-01 20:12:45.866 [ERROR] - DbPreferences.GetKeyID: Failed to get KeyID. Error: Connection refused. Check that the hostname and port are correct and that the postmaster is accepting TCP/IP connections.
2016-07-01 20:12:45.867 [WARN ] - The Citrix Desktop Service failed to connect to the Citrix Configuration Database.
Please ensure the Citrix Configuration Database Service is running before starting the Citrix Desktop Service.
The service will retry connecting to the Citrix Configuration Database in approximately 15 seconds. Retry attempt: 2.
Error details:
Exception 'LOCAL registry could not be initialized.' of type 'RegistryNotFoundException'

To check present status of the service

          # service postgresql status

Restart postgressql service on the VDA

#service postgresql restart

Problem Cause

 postgresql service was stopped on the Linux VDA. This service is required for the VDA agent to start