0xC1900101 error when Windows 10 upgrade fails after the second system restart

Applies to: Windows 10Windows 10 Version 1607Windows 10 Version 1511


A system upgrade from Windows 10 Version 1511 to Windows 10 Version 1607 fails and generates the following error message:
0xC1900101 - 0x40017

This error occurs after the second system restart. After this error occurs, the system rolls back to the previous version.


This problem occurs because the computer has Citrix Virtual Delivery Agent (VDA) installed. Citrix VDA installs device drivers and a file system filter driver (CtxMcsWbc). This Citrix filter driver prevents the upgrade from writing changes to the disk. This triggers the system rollback.


To resolve this problem, follow these steps:

  1. Uninstall Citrix VDA (VDAWorkstationSetup_7.11).
  2. Run the Windows upgrade again.
  3. Reinstall Citrix VDA.


To work around this problem, follow these steps:

  1. Disable the Citrix MCS cache service in the registry by changing the start value from 0 to 4, as shown in the following screen shot.

  2. Delete the CtxMcsWbc entry in the following subkey:
  3. Restart the computer, and then try the upgrade again.

More Information

This problem has been observed in upgrades to Windows 8.1 and Windows 8 also.