Symptoms
The VMware Horizon Drag and Drop feature may not work when the Group Policy "Do not allow drive redirection" at "Computer Configuration - Administrative Templates - Windows Components - Remote Desktop Services - Remote Desktop Session Host - Device and Resource Redirection" is enabled.
Alternatively this registry also needs to be validated and we need to ensure the value for "fDisableCdm" ( REG_DWORD) is set to 0 at "HKLM\SOFTWARE\Policies\Microsoft\Windows NT\Terminal Service".
Purpose
This article discuss about a scenario of Windows Group Policy blocking the functionality of Horizon Agent's Client Drive Redirection / Drag and Drop Feature.
There may be scenarios when you strictly need to disable the Client Drive Redirection capability but still want to use Drag and Drop. Please do not utilise this Windows group policy or deactivate the client drive redirection capability during the Horizon Agent installation in this case. Instead, under the Horizon Smart Policies Section of VMware Dynamic Environment Manager [ DEM ], deactivate Horizon Client Drive Redirection on a user level. For more information please refer: Configure Horizon Smart Policies for User Environment Settings
The smart policy toggles the following registry based on the setting configured on Horizon Smart Policy at DEM for redirection
Reg_path: Computer\HKEY_CURRENT_USER\SOFTWARE\Policies\VMware, Inc.\VMware TSDR\<session_num>Reg_Key: DisabledReg_Value: 1
Cause
The Horizon Drag and Drop feature is dependent on the Horizon Client Drive Redirection feature. If registry fDisableCdm is set to 1 or if "Do not allow drive redirection" GPO is enabled, the operating system would block any drive redirection from the client to agent and viceversa
Impact / Risks
Horizon Drag and Drop feature and Client Drive Redirection features are impacted
Resolution
* Always ensure the GPO "Do not allow drive redirection" ("Computer Configuration - Administrative Templates - Windows Components - Remote Desktop Services - Remote Desktop Session Host - Device and Resource Redirection" ) is disabled or the value of fDisableCdm ( REG_DWORD) is set to 0 at "HKLM\SOFTWARE\Policies\Microsoft\Windows NT\Terminal Service" to use the Drag and Drop or Client Drive Redirection feature. * This applies to both RDSH and VDI Desktop Agents.
Workaround
Note: Toggling fDisableCdm from 0 to 1 or viceversa does not require restart of the machine. The session needs to be reconnected for the settings to take effect. If its instant clone, ensure the registry change is performed at the master image.
