Linux Render Video To mp4
At first, I solved problem with starting of Kdenlive (video editor in linux universe) by deleting Kdenlive’s config file ($HOME/.config/kdenliverc) and restart Kdenlive...
source: kdenlive.org: Troubleshooting
Render to mp4?
But then I was unable to render my video to mp4 format. Only in webm and other similar non-proprietary codecs.
Solved
And I rendered my video manually:
melt avformat:input.webm -consumer avformat:output.mp4 acodec=aac vcodec=libx264