SUMMARY Night Color feature is no longer working on neon unstable. Its KCM displays "Failed to connected to the Window Manager" inline message on top. EXPECTED RESULT Night Color feature should work. SOFTWARE/OS VERSIONS Operating System: KDE neon Unstable Edition KDE Plasma Version: 5.20.80 KDE Frameworks Version: 5.78.0 Qt Version: 5.15.2
Can reproduce, also on KDE Neon Unstable.
Working for me, FWIW.
Hmm. It seems as if https://invent.kde.org/plasma/kwin/-/merge_requests/530 is the relevant commit / MR. The error message comes from https://invent.kde.org/plasma/plasma-workspace/-/blob/master/libcolorcorrect/compositorcoloradaptor.cpp which tries to connect to the color correct thingy of KWin via DBus if I understood the code correctly. This path doesn't seem to exist though if I search for it within qdbusviewer.
It is now guarded by: if (KWIN_BUILD_CMS) please confirm against the build output that this dependency was found. or check kwin debug information to confirm the plugin was loaded.
Indeed, Neon unstable built without lcms2 as a Build-Dep. I have now adjusted the build config, and the latest KWin update fixes the problem for me. @Patrick: Please reopen if against expectations the latest KWin (kwin-x11 version 4:5.20.5+p20.04+git20210106.0811-0) does not fix the problem for you.