Following the instructions in https://bugs.kde.org/show_bug.cgi?id=432016#c2 didn't help immediately, even with deleting additionally ~/.config/kdenlive-layoutsrc and ~/.config/kdenliverc, but when I reinstalled Kdenlive, it worked. Except (as previously) it showed very dark text on dark background, hardly readable. So I changed the theme and the result was even worse: no text appeared in the menus when I dropped them down. So I blindly clicked something in a subemnu of Setting, first time probably changing colours and next time hiding the menu bar. The alt key didn't activate the menu, so I decided to reinstall again. Now, despite trying deleting the abovementioned files and directories, and even reinstalling, I keep getting the following output on startup, after which the splash screen disappears and the process exits: mlt_repository_init: failed to dlopen /usr/lib/mlt/libmltrubberband.so (librubberband.so.2: cannot open shared object file: No such file or directory) mlt_repository_init: failed to dlopen /usr/lib/mlt/libmltopencv.so (/usr/lib/mlt/libmltopencv.so: undefined symbol: _ZN2cv7Tracker6updateERKNS_11_InputArrayERNS_5Rect_IdEE) mlt_repository_init: failed to dlopen /usr/lib/mlt/libmltrtaudio.so (librtaudio.so.6: cannot open shared object file: No such file or directory) mlt_repository_init: failed to dlopen /usr/lib/mlt/libmltsox.so (libsox.so.3: cannot open shared object file: No such file or directory) Invalid metadata for "glsl.manager" Failed to parse "glsl.manager" Invalid metadata for "movit.convert" Failed to parse "movit.convert" Invalid metadata for "movit.crop" Failed to parse "movit.crop" Invalid metadata for "movit.resample" Failed to parse "movit.resample" Invalid metadata for "movit.resize" Failed to parse "movit.resize" Invalid metadata for "jack" Failed to parse "jack" Invalid metadata for "audiochannels" Failed to parse "audiochannels" Invalid metadata for "audioconvert" Failed to parse "audioconvert" Invalid metadata for "data_feed" Failed to parse "data_feed" Invalid metadata for "imageconvert" Failed to parse "imageconvert" Invalid metadata for "avcolour_space" Failed to parse "avcolour_space" Invalid metadata for "avcolor_space" Failed to parse "avcolor_space" Invalid metadata for "avdeinterlace" Failed to parse "avdeinterlace" Invalid metadata for "swscale" Failed to parse "swscale" Invalid metadata for "swresample" Failed to parse "swresample" Invalid metadata for "telecide" Failed to parse "telecide" Invalid metadata for "deinterlace" Failed to parse "deinterlace" Invalid title/identifier for "crop_detect" Failed to parse "crop_detect" Unknown asset "avfilter.acompressor" Unknown asset "avfilter.aecho" Unknown asset "avfilter.agate" Unknown asset "avfilter.atadenoise" Unknown asset "avfilter.bwdif" Unknown asset "avfilter.deblock" Unknown asset "avfilter.dedot" Unknown asset "avfilter.deflate" Unknown asset "avfilter.derain" Unknown asset "avfilter.doubleweave" Unknown asset "avfilter.field" Unknown asset "avfilter.framestep" Unknown asset "avfilter.fspp" Unknown asset "avfilter.graphmonitor" Unknown asset "avfilter.hqdn3d" Unknown asset "avfilter.inflate" Unknown asset "avfilter.lagfun" Unknown asset "avfilter.random" Unknown asset "avfilter.removegrain" Unknown asset "avfilter.separatefields" Unknown asset "avfilter.shuffleplanes" Unknown asset "avfilter.sr" Unknown asset "avfilter.tmix" Unknown asset "avfilter.w3fdif" Unknown asset "avfilter.weave" Unknown asset "avfilter.yadif" Unknown asset "frei0r.baltan" Unknown asset "frei0r.bgsubtract0r" Unknown asset "frei0r.bigsh0t_eq_mask" Unknown asset "frei0r.bigsh0t_eq_to_rect" Unknown asset "frei0r.bigsh0t_hemi_to_eq" Unknown asset "frei0r.bigsh0t_rect_to_eq" Unknown asset "frei0r.bigsh0t_stabilize_360" Unknown asset "frei0r.bigsh0t_transform_360" Unknown asset "frei0r.delay0r" Unknown asset "frei0r.delaygrab" Unknown asset "frei0r.facebl0r" Unknown asset "frei0r.facedetect" Unknown asset "frei0r.lightgraffiti" Unknown asset "frei0r.lightgraffiti" Unknown asset "movit.unsharp_mask" Unknown asset "region" Unknown asset "sox" Unknown asset "sox" Unknown asset "sox" Unknown asset "sox" Unknown asset "sox" Unknown asset "sox" Unknown asset "sox" Unknown asset "timewarp" Unknown asset "opencv.tracker" Unknown asset "opencv.tracker" Segmentation fault (core dumped)
It seems that something is wrong with your setup. Can you try to use the appimage (https://kdenlive.org/en/download/) it avoids some packaging issues and is usually the most stable choice.
Some more questions: can you please check if mlt is installed? Please check also if using the appimage or flatpak (https://kdenlive.org/en/download/, latest version is 20.12.3 at the moment) solves your problem and report back?
Yes, mtl is installed (6.24.0-1). Yes, the AppImage version works fine. Thanks very much! And it seems to have (though I might not remember correctly) more Color Themes and less Styles available. It's 20.12.2 though and neither showing in Pamac, nor notifying of an available upgrade in any other way. So I'll probably switch to Flatpak.
Thanks for your reply and the report in general :)! I am closing this now as this is a packaging issue with a source we probably have no impact to and it works with the appimage (and probably with the flatpak too) as you told us.