Error  " A device attached to the system is not functioning" is seen accessing a USB drive in a custom application.

Issue was seen after upgrade from VDA 7.15 to VDA 1912 CU4.

 

To stop the issue happening in published applications and published desktops with Client Mapped Drives add following registry on the VDI and reboot.
 
Registry Path : HKEY_LOCAL_MACHINE\System\Currentcontrolset\services\picadm\Parameters
Name: DisableFullStreamWrite
Type: REG_DWORD
Data: 0x01

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Problem Cause

See also https://support.citrix.com/article/CTX285248