Eval Licenses have to be converted to normal licenses first. See here.
Even from Standard Core the update doesnt seem to work.1)
DISM /online /Set-Edition:ServerDatacenterCor /ProductKey:WMDGN-G9PQG-XVVXX-R3X43-63DFG /AcceptEula #or DISM /online /Set-Edition:ServerDatacenter /ProductKey:WMDGN-G9PQG-XVVXX-R3X43-63DFG /AcceptEula
after Restart:
slmgr /ipk H3RNG-8C32Q-Q8FRX-6TDXV-WMBMW slmgr /ato
You MUST install this software using the desktop experience edition.
DISM /online /Set-Edition:ServerDatacenter /ProductKey:XXXXX-XXXXX-XXXXX-XXXXX-XXXXX /AcceptEula
after Restart:
slmgr /ipk XXXXX-XXXXX-XXXXX-XXXXX-XXXXX slmgr /ato
The DISM command does not set the product key, so the slmgr is essential.
Even from Standard Core the update doesnt seem to work.2)
DISM /online /Set-Edition:ServerDatacenterCor /ProductKey:WMDGN-G9PQG-XVVXX-R3X43-63DFG /AcceptEula
after Restart:
slmgr /ipk XXXXX-XXXXX-XXXXX-XXXXX-XXXXX slmgr /ato
slmgr -rearm