When starting xpra on a bare-minimum Fedora system, I see this:
Error running "xauth add :100 MIT-MAGIC-COOKIE-1 ...": [Errno 2] No such file or directory
Trying to run xauth manually confirms that it is not installed:
$ xauth bash: xauth: command not found
The package name is xorg-x11-xauth:
$ rpm --query --whatprovides /usr/bin/xauth xorg-x11-xauth-1.0.9-5.fc24.x86_64
It's actually a Fedora bug, sorry: https://bugzilla.redhat.com/show_bug.cgi?id=1309804
this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/1126