The remote session was disconnected because there are no Terminal Server license servers available to provide a license

Problem:

User could not connect to any Citrix application, and whenever launching a Citrix application, it throws the error " The remote session was disconnected because there are no Terminal Server license servers available to provide a license"

Solution:

To Resolve the License error remove the MSLicensing registry key on the user desktop by following the below steps.

1. On the client, open Registry Editor. To open Registry Editor, click Start, click Run, type regedit, and then click OK.
2. Locate, and then click, the following key in the registry:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSLicensing

3. On the Registry menu, click Export Registry File.
4. In the File name box, type mslicensingbackup, and then click Save. 
5. If you need to restore this registry key in the future, double-click mslicensingbackup.reg.
6. On the Edit menu, click Delete, and then click Yes to confirm the deletion of the MSLicensing registry subkey.
7. Close Registry Editor, and then restart the computer (when the client is restarted, the missing registry key is rebuilt).
8. Now check the Citrix applications.

Citrix Client Error 2320

Please find the solution in the attached doc for Citrix Client Error 2320

1.) Please clear user profile in his/her computer

2.) Change he value of Registry Key (EnableLockdown)to Zero as shown in the screenshot. The default is 1

HKEY_LOCAL_MACHINE\SOFTWARE\Citrix\ICA Client\Engine\Lockdown Profiles\All Regions\EnableLockdown

Single Sign On (SSO)

As soon as user login to his/her computer with his/her credentials the PNAgent should automatically popup all applications to which user has access. If this doesn't work please follow the below steps.

Open task manager and check "ssonsvr.exe" is running. This service is essential for the single sign-on to work properly.

If the service isn't running, do the following:  

1)Un-install the client

2)Delete PNAgent folder under C:\Documents and

Settings\user profile\Application Data\Citrix

3)Delete ICAClient folder under C:\Documents and Settings\user profile\Application Data

4)Delete the following registry keys: ICA Client, PNAgent, Program Neighborhood Agent under:

HKEY_CURRENT_USER\Software\Citrix

5)Delete the following registry keys:ICA Client, PNAgent under:

HKEY_LOCAL_MACHINE\Software\Citrix

6)Reboot the PC

7.) Install the new Citrix client

8)Open the registry and navigate to:

HKLM\System\CurrentControlSet\Control\NetworkProvider\HwOrder

9)Double-click on ProviderOrder string and place PnSson in the beggining of the string

10) Do the same for    HKLM\System\CurrentControlSet\Control\NetworkProvider\Order

11) Reboot the PC

Start the PN agent, and make sure  you'r able to see "SSONSVR.EXE" service as running on user system taskmanager.

So now application list will automatically popup in PNAgent as soon as user logs into the computer.