The unattended uninstallation of jabref ( uninstall.exe /S ) doesn't work anymore since version 2.9.1
Until version 2.9.0 it worked well. Since 2.9.1 a popup shows up, which asks you, if you are sure with uninstalling jabref. After clicking on Yes everything works as it should.
The popup needs to be suppressed in unattended uninstallation mode.