Hello Patrick, I guess this is the same as described in bug #996726.
And I was able to workaround by installing libkdecorations2-5v5_5.21.5-2_amd64.deb. Kind regards, Bernhard Core was generated by `/usr/bin/kwin_x11 --replace'. Program terminated with signal SIGSEGV, Segmentation fault. #0 0x00007ffff5d1f510 in KDecoration2::DecorationSettings::font (this=this@entry=0x5555556f0880) at /usr/include/c++/11/bits/unique_ptr.h:173 173 /usr/include/c++/11/bits/unique_ptr.h: Datei oder Verzeichnis nicht gefunden. [Current thread is 1 (Thread 0x7ffff047b9c0 (LWP 7026))] (gdb) set width 0 (gdb) set pagination off (gdb) bt #0 0x00007ffff5d1f510 in KDecoration2::DecorationSettings::font (this=this@entry=0x5555556f0880) at /usr/include/c++/11/bits/unique_ptr.h:173 #1 0x00007ffff5d1f737 in operator() (__closure=<synthetic pointer>) at ./src/decorationsettings.cpp:19 #2 KDecoration2::DecorationSettings::DecorationSettings (this=0x5555556f0880, bridge=0x55555573e230, parent=<optimized out>) at ./src/decorationsettings.cpp:34 #3 0x00007ffff7d68add in QSharedPointer<KDecoration2::DecorationSettings>::create<KWin::Decoration::DecorationBridge*> () at /usr/include/c++/10/new:175 #4 KWin::Decoration::DecorationBridge::init (this=0x55555573e230) at ./decorations/decorationbridge.cpp:121 #5 KWin::Decoration::DecorationBridge::init (this=0x55555573e230) at ./decorations/decorationbridge.cpp:110 #6 0x00007ffff7e6d5a7 in KWin::Workspace::Workspace (this=0x55555574b450) at ./workspace.cpp:187 #7 0x00007ffff7dc6990 in KWin::Application::createWorkspace (this=this@entry=0x7fffffffe3a0) at ./main.cpp:272 #8 0x000055555555d41e in KWin::ApplicationX11::continueStartupWithScreens (this=0x7fffffffe3a0) at ./main_x11.cpp:272 ...
