I have migrated more than 50 many types virtual machines from Citrix to VMware with Converter Standalone.
May be you know there are a lot of post,blog,forum etc. about solution of this problem but all of them is not complete solutions. I try to provide correct order and method for this produre.
You can use below method for all type Windows Server (2008,2012,2016). This is the correct order!
Note1: Please dont reboot vm until last step!
Note2: Apply in following order!

1. After getting blue screen (SYSTEM_THREAD_EXCEPTION_NOT_HANDLED) error, Please reboot your server and type F8 before booting.
Boot your server with Safe Mode with Command Prompt

2. Enable “msiserver” service to run Programs Add/Remove.
REG ADD “HKLM\SYSTEM\CurrentControlSet\Control\SafeBoot\Minimal\MSIServer” /VE /T REG_SZ /F /D “Service”

3. start msiserver service.
net start msiserver

4. run Programs Add/Remove
appwiz.cpl

Uninstall all Citrix Xen Related Tools and Drivers but do not! reboot. Please “no” for uninstall questions.
5. Run explorer.exe to delete xen system files.
c:\Windows\System32\drivers and search xen*.sys > shift+delete

6. Open Device Manager to Uninstall Hidden Xen Drivers
type devmgmt.msc in your cmd > show hidden devices > uninstall all xen drivers.


7. Delete all register records
- Please delete all register records starting with xen* in CurrentControlSet1, CurrentControlSet2 and if exist another CurrentControlSetX.
HKLM\CurrentControlSet*\Services\xen*

- Please delete two UpperFilters line ( Only UpperFilters line!)
HKLM\CurrentControlSet\Control\Class
{4d36e96a-xxxxx} > UpperFilters

{4d36e97d-xxxxx} > UpperFilters

Then Reboot and Enjoy!
Thanks