dbus-session-bus software package provides virtual package provided by dbus-x11, dbus-user-session, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install dbus-session-bus
dbus-session-bus is installed in your system.
Make ensure the dbus-session-bus package were installed using the commands given below,
$ sudo dpkg-query -l | grep dbus-session-bus*
You will get with dbus-session-bus package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Virtual packages |
| Package | dbus-session-bus |
| Version | |
| Description | virtual package provided by dbus-x11, dbus-user-session |
| Sub Section | Virtual |