No module named xpra.dotxpra on Debian Buster

[F. Vogel]

Hi!

Server: Debian Buster
# dpkg -l | grep -E "xpra|winswitch"
ii python3-xpra 3.0.9-r26132-2 amd64 tool to detach/reattach running X programs
ii winswitch 0.12.23-2 all tool to start and control remote sessions
ii xpra 3.0.9-r26132-2 amd64 tool to detach/reattach running X programs
ii xpra-html5 3.0.9-r26132-2 amd64 html5 xpra client

Client: Linux Mint 19.3
$ dpkg -l | grep -E "xpra|winswitch"
ii python3-xpra 3.0.9-r26132-2 amd64 tool to detach/reattach running X programs
ii winswitch 0.12.23-2 all tool to start and control remote sessions
ii xpra 3.0.9-r26132-2 amd64 tool to detach/reattach running X programs

Xpra itself works fine, but using winswitch does not:
"You have requested an xpra session but this server does not support it"

When running the server from the CLI I get the following message:
[EE] 2020/29/04 19:07:38.816622 WinSwitchServer?.assign_virt_utils() failed to load xpra, make sure it is installed: No module named xpra.dotxpra

There is a very old ticket with the same issue (https://winswitch.org/trac/ticket/219). According to that i tried to link /usr/lib/xpra to a lot of locations without any effort.

If you need more input please let me know!

Regards,
Frank