There is HIGH master issue for this in the bug tracker of Back in Time, please track the status there.
https://github.com/bit-team/backintime/issues/921 We (a new team taking over the responsibilities to develop and maintain Back in Time) are working on this issue and other issues to stabilize (fix bugs, don't add new features) the next release that hopefully is ready before the next Debian freeze window. As a first indicative diagnosis of this issue: The CLI "backintime" from "backintime/common" does require a D-Bus service end point that is only contained in the "backintime/qt" source folder (file serviceHelper.py which manages Udev rules for Back In Time) so if the CLI and GUI part are packaged into two different packages the CLI does still not work without the installed GUI package. This is a "lack of enough documentation" issue on our side I think but also a bug in Back in Time CLI that should be more fault-tolerant to ignore a missing serviceHelper. As a first work-around: If you build from source (and all depdendencies are installed!) you always have to "make install " twice cd common ./configure make # "make test" is not yet reliable here due to the missing serviceHelper installed later make install cd ../qt ./configure make make install # this actually installs the missing serviceHelper.py running as root on the system D-Bus cd ../common make test # no the tests should be green
