After installation of TL 2019: Tlmgr claims that directory 2018 is not writable

[Alois Steindl]

After successfully installing the latest TeXLive 2019 on a Windows 10 
system I encounter a strange problem: When calling tlmgr (actually it is 
tlshell), I receive the message "E:/texlive/2018 is not writable. You 
can probably not do much. Are you sure you want to continue?"

In the window I see the entries "Root at E:/texlive/2018", tlmgr: 
r49931, tlshell: r50042.

Of course, I start the program from the icon in the 2019 folder and TL 
is installed in e:/texlive/2019.

I couldn't find any setting, which might force the root at e:/texlive/2018.

Update: In the meantime I entered the command from the shell

tlshell option repository http://mirror.ctan.org/systems/texlive/tlnet

and now it looks fine. Also tlmgr and tlshell indicate newer versions 
(R51232, R51231). It seems, that starting tlmgr from the icon (Start 
menu -> TeX Live 2019 -> TeX Live Manager) causes the troubles, it calls 
the 2018 program, although the menu entry points to tlshell in the 2019 
tree.

Best wishes

Alois