That's another regression blocked 2.28 in Ubuntu caught by our testing infrastructure The C example from https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=931807 can be used as a tetcase Doing $ gcc bug.c -o bug `pkg-config --libs --cflags webkit2gtk-4.0` $ xvfb-run ./bug displays a 'Error running javascript:' the same example works fine using 2.26
(updated title, it's not any javascript that is buggy but specific examples)