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Session Crashes when Shadowing


When shadowing a published desktop with a resolution greater than or equal to 1280×1024, the session of the user who is shadowing might terminate when the ICA session Window is resized. A dialog box stating “Virtual Driver error” error message might also be displayed to the user.


The client disconnects because it cannot accept the value of Thinwire Cache Power proposed by the server because the value exceeds the default limits of the client.


You need to increase the value for the Thinwire Cache Power.

Warning!!!: Using the Registry Editor incorrectly can cause serious issues with the operating system that might require you to reinstall the operating system. Citrix does not guarantee that the issues resulting from the incorrect use of Registry Editor can be resolved. Use the Registry Editor at your own risk. Ensure that you make a backup of the registry before you edit it.

On the endpoint of the user who is shadowing, create the Tw2CachePower value under the following registry key:

HKEY_LOCAL_MACHINE\SOFTWARE\Citrix\ICA Client\Engine\Configuration\Advanced\Modules\Thinwire3.0

The following are the details of the registry key:

  • Value: Tw2CachePower
  • Type: REG_SZ
  • Data: 19 – 25

Even though the maximum value specified for Tw2CachePower is 25, a value of 24 covers most scenarios. The client device must be able to allocate the memory of 2^24 bytes, if cache power of 24 is used.

If you are shadowing from a XenApp 6 published Desktop, then you need to add the Tw2CachePower value under the following key:

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Citrix\ICA Client\Engine\Configuration\Advanced\Modules\Thinwire3.0

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