Python 3 is recommended. This article left in place for reference only.

Description

The D-Bus Python modules let the CrossOver application installation wizard detect the insertion of media such as CD-ROMs and USB flash drives. This lets it look for Windows installers and automatically pick the appropriate application profile.
This is not needed to run Windows applications.

Resolution

Python 3 is recommended. See the Missing Python 3 D-Bus support page.

On CrossOver 17 and greater, the simplest solution to fix this issue is to run:

/path/to/cxoffice/bin/cxfix dbus

Or add --show-all to see how CrossOver would fix it on your platform and others.

Alternatively you may try one of the commands below.
Arch Linux : pacman -Syu python2-dbus
Debian : apt-get install python-dbus
Fedora : yum install dbus-python
openSUSE : zypper install dbus-1-python

Notes:

• cxfix --show-all may have more up-to-date fixes.
• The commands above likely also apply to derivatives of the mentioned Linux distributions. So for instance a fix for Debian is likely also applicable to Ubuntu, Linux Mint, Deepin and Pop! OS. Similarly a fix for Fedora will likely also work on Red Hat Enterprise Linux, CentOS, etc.