Experiencing issue with com port redirection in XenApp 7.6 shared desktop. COM port redirection appears to work the first time but subsequent logins fail requiring a reboot of the server.

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Solution 1 - Binary Fix

The issue seems to be related to an available Binary fix: 

1. Replace rpm.dll under C:\Program Files (x86)\Citrix\System32\ of TSVDA with the private binary; 
2. Reboot the VDA to make the private work; 
3. Verify if this issue is corrected. 

Note: Contact Citrix Technical Support to request the private binary fix.

Solution 2 - XenApp 7.8

This private fix is publicly available with XenApp 7.8. Refer to Citrix Documentation - Fixed issues in XenApp 7.8 and XenDesktop 7.8.

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Problem Cause

RootCause: The COM connection of previous session is not unbind on  CStack::DisconnectNotify(), because the stack has been disconnected before CStack::DisconnectNotify(). This issue should be caused by fix of BUG0487797.

Experiencing issue with com port redirection in XenApp 7.6 shared desktop. COM port redirection appears to work the first time but subsequent logins fail requiring a reboot of the server.