SUMMARY Well, this may be not directly a bug. But when the VDPAU (video decoding acceleration API) is uninstalled with "sudo apt-get remove mesa-vdpau-drivers libvdpau1 vdpauinfo" also the dolphin file manager is removed from the system. This is a somewhat strange behavior, - for a file manager. STEPS TO REPRODUCE 1. Execute the command "sudo apt-get remove mesa-vdpau-drivers libvdpau1 vdpauinfo" in the terminal OBSERVED RESULT The dolphin file manager is removed along the VDPAU packages. EXPECTED RESULT When VDPAU is uninstalled, dolphin should not be removed. And if dolphin needs any form of "video acceleration" (?), it should use the VA-API instead of VDPAU. SOFTWARE/OS VERSIONS Linux/KDE Plasma: Kubuntu 18.04 (available in About System) KDE Plasma Version: 5.12.9 KDE Frameworks Version: 5.44.0 Qt Version: 5.9.5 ADDITIONAL INFORMATION The effective reason to remove VDPAU is because it is broken for some hardware. As of January 2020 this is true for most newer Radeon (r600) MESA driver releases. In most cases, with some rare exceptions, the VA-API is working stable. So a switch to that video decoding acceleration API would be a good workaround.
Please report packaging issues to the bug tracker of your distribution.
Thanks Christoph Feck for the fast answer. I have now done this so this error report can be closed. It think this is a Kubuntu related issue and not a general KDE dolphin one. ;-) https://bugs.launchpad.net/ubuntu/+source/dolphin/+bug/1861167