SUA-SDK, CSH crashes on Citrix XenApp system

We have got many issues reported for SUA SDK, where the korn/ C shell crashes.

While the C shell crashes just after launching the korn shell crashes as soon we run command like clear.

With further investigation, we had found that generally this is because of some anti-virus or Citrix software which inject some code into every process during start-up assuming them to be proper Win32 process. SUA processes we know behave a little different than other Windows processes especially during start up so this looks to be a feasible possibility.

Uninstalling XenApp citrix application does resolves the issue but this was not feasible solution on most of the scenarios.

Hence with further troubleshooting / research and investigation we noticed that there were two citrix drivers were interfering with SUA: rskcore.sys and ctxpidmn.sys

From the crash dumps we could see ctxpidmn.dll queuing which was coming from ctxpidmn.sys (Citrix driver pool allocation). To fix ctxpidmn.sys, follow the steps as per               

  • Run regedit.

  • Add following registry key.

  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\ctxpidmn

    Type: String

    Name: UviProcessExcludes

    Value: csh ==>For C shell

  • Separate with colon if necessary for other commands. e.g.) vi;csh;yacc;clear

  • Reboot server to enable the setting.


Rskcore.sys, is a core part of Citrix Edgesight which is a monitoring agent for citrix. Unfortunately, there was no registry option or any other option available to exclude SUA processes and hence this driver needs to be removed.


With this the SUA works and users can launch C shell. Run the clear command from Korn shell. The steps discussed are based out of testing and alternate workaround.