Storage Migration Service stucks at 30% - Can't unjoin domain

Hello again,

after three months we finally gave it a new try.
The migration succeeded.
There was quite a few maintanance things we did, I will tell you the most likely reasons:

-since March a new admin center version and SMS version released
-Also new windows updates was released which were installed on all relevant servers
-We checked the eventlog on the source server for any errors and fixed them
-> NTP, shares, ....
-we also did a winsock reset:

Reset Winsock control.

Restoring transaction logs.
fsutil resource setautoreset true C:\

Restoring TPC/IP.
netsh int ip reset

Restoring Winsock.
netsh winsock reset

Restoring default policy settings.
netsh advfirewall reset

Restoring the DNS cache.
ipconfig /flushdns

Restoring the Proxy.
netsh winhttp reset proxy

Some of these may be the solution!