After the apt-get dist-upgrade last night, the characters in the system title bar became all the squares.
To check out the fonts configuration, we can use
sudo apt-get install dconf-tools
The issue command
Then expand org>gnome>desktop>wm>preferences: then choose the “titlebar-font”, first of all, read the Default , in my case it was “Cantarell Bold 11”. Then I opened the tweak tool, search the “Cantarell” and found that the font was corrupt.
To solve this, I decide to reinstall the font and see if it works.
In linux, we can install or remove the font by apt-get command, so:
remove the Cantarell font:
apt-get purge fonts-cantarell
apt-get install fonts-cantarell
And the system will configure the font automatically.