TeXLive 2020, Can't use lualatex on Windows

[Hoffmann, Jobst]

Hi all,

I try to compile a small LaTeX-file (the content doesn't matter), it
ends with an error message

Der Prozedureinsprungpunkt "u8getmbstring" wurde in der DLL
"E:\texlive\2020\bin\win32\luahbtex.dll" nicht gefunden

the English version would be something like

The procedure entry point "u8getmbstring" wasn't found in the DLL
"E:\texlive\2020\bin\win32\luahbtex.dll"

The same happens when I try to update my TeXLive 2020 installation using
TLShell.exe (tlmgr works fine).

If I have a look at that DLL, I see a string "u8getmbstring". What can I
do?

Kind regards
Jobst
-- 
Prof. i.R. Dr. Jobst Hoffmann       Tel:   +49 (241) 6009-5 31 59
Fachhochschule Aachen Abt. Jülich   Fax:   +49 (241) 6009-5 31 89
Fachbereich 09                      email: j.hoffmann at fh-aachen.de