U-AIR issue: Virtual Lab Manager is disconnected

The following error message occurs when running the U-AIR wizard:
 

Virtual Lab Manager is disconnected

The following error messages can be found in the Veeam.AIR.<U-AIR type> log file:

[timestamp] Error    Virtual Lab Manager is disconnected. (Veeam.Backup.Common.CommonException)
[timestamp] Error    Server stack trace: 

[timestamp] Error       at Veeam.AIR.SessionManager.CSessionManager.StartSession(CSessionRequestData requestData)


You are unable to perform item level restore.

Virtual Lab Manager is not able to connect to Enterprise Manager. All virtual lab requests submitted by different users are listed on the Lab Requests tab in Veeam Backup Enterprise Manager. Administrators working with Veeam Backup Enterprise Manager can approve submitted lab requests, reject the requests, or prolong the time for which a requested virtual lab should run.

The version of U-AIR tool you are using must match the version of Veeam Backup & Replication you have installed. Current U-AIR tools can be found in the “AIR” folder of the installation media for your version of Veeam Backup & Replication.

Please check the following:

1. Enterprise manager and Virtual Lab Manager are running in the same domain. 

2. Open the Registry Editor and find the Computer\HKEY_LOCAL_MACHINE\SOFTWARE\VeeaM\Veeam U-AIR key. Make sure the IP address and the port specified coincide with the IP and port the EM server actually uses.