Control: tag -1 + moreinfo bullseye sid If you cannot switch to console with Ctrl-Alt-F2 then this is a strong indicator that the bug is in the kernel, probably nouveau. If you can reproduce this reliably it would help a lot if you could provide the output of these commands after the bug has happened: dmesg strace -f -p $(pidof ksplashqml) 2>&1 | dd bs=1k count=20 journalctl -ab You may have to run some of them as root.