After upgrading to Dolphin 18.04 it resets all previous configuration of panels like custom launchers and such. That should not happen. It should take what was previously configured and use it.
Turns out the dolphinui.rc version number needs an update. Maybe it should perform that automatically.
After upgrading from which version?
Upgraded from 17.08
Weird, actually we don't install the dolphinui.rc file anymore (since 17.08). Where did you had to increase the version number?
If you can provide the information requested in comment #4, please add it.
It is a distribution specific configuration file. So if a distro ships a configured toolbar you need to manually update the file or the distro needs to update that file everytime a new dolphin version comes out.
I see. I'm not sure we can do something from out side then.
Please report downstream if the file is provided by your distro.