Because of a protocol error, this session will be disconnected. Please try connecting to the remote computer again

When a user remote controls another user's session using RDS Manager or Terminal Services Manager on a Windows Server 2008-based computer, and then stops remote controlling, one or both sessions are disconnected with the following error:

Remote Desktop Disconnected

Because of a protocol error, this session will be disconnected. Please try connecting to the remote computer again.

CAUSE

This problem occurs if Remote Desktop Connection Client version 6.0.6001 or 6.0.6002 is used with the highest RDP Compression setting. Windows Server 2008 SP1/SP2 defaults to a lower RDP Compression setting, and thus will only exhibit the above symptoms if the setting has been changed to "Optimized to use less network bandwidth", which is the maximum. Windows Server 2008 R2 defaults to the maximum RDP Compression setting.

WORKAROUND

Change the RDP Compression setting on the server to "Balances memory and network bandwidth" (recommended) or "Optimized to use less memory" using Group Policy. If using Windows Server 2008 R2 you may also choose "Do not use an RDP compression algorithm". An alternative workaround is to use a different Remote Desktop Connection Client version than those mentioned above, however, this may not be practical. Below are instructions for making the change to the local group policy; if preferred you can use a domain group policy instead.

Windows Server 2008 R2

1. Logon to the Remote Desktop Services Session Host computer as an administrator
2. Start--Run gpedit.msc
3. In the left pane, under Computer Configuration, navigate to following:

Administrative Templates\Windows Components\Remote Desktop Services\Remote Desktop Session Host\Remote Session Environment

4. In the right pane, double-click on Set compression algorithm for RDP data
5. Select Enabled, and choose Balances memory and network bandwidth
6. Click OK to save the change

Windows Server 2008 (SP1 or SP2)

1. Logon to the Terminal Services computer as an administrator
2. Start--Run gpedit.msc, click Continue if prompted by UAC
3. In the left pane, under Computer Configuration, navigate to following:

Administrative Templates\Windows Components\Terminal Services\Terminal Server\Remote Session Environment

4. In the right pane, double-click on Set compression algorithm for RDP data
5. Select Enabled, and choose Balances memory and network bandwidth
6. Click OK to save the change