I was unable to start barrier after an update. The GUI would crash immediately. I tried running it in a terminal ( by running the command barrier directly) and got the error:

▶ barrier               
Fontconfig warning: FcPattern object weight does not accept value [0 205)
[1]    8790 segmentation fault (core dumped)  barrier

Some googling led me to this fix:

sudo rm /var/cache/fontconfig/*
rm ~/.cache/fontconfig/*
fc-cache -r

After those three commands, I was able to launch barrier without issue.