VDI Issue - Virtual Desktop Under Maintenance

I had this incident reported to my team once in a blue moon. users not able to access to their virtual desktops, with below error.

The desktop that you are trying to restart is currently undergoing maintenance. Contact your system administrator.

Issues :

Users not able to access virtual desktop because of the desktop is still under 
maintenance.

Troubleshooting 

1.  Launch Citrix Desktop Studio, and search for the specific virtual desktop. You may focus on the virtual desktop name or the user ID configured to it.
2.  At that virtual desktop, you will see Maintenance Mode is enabled. if you right click at the target virtual desktop, you will see there in an option to Disable maintenance mode.
   

Resolution :

Click at Disable maintenance mode in order to allow user to use it. Maintenance Mode status will then change to Disabled. Get user to retry.