Solution for Flash Square Garbled Text in Ubuntu Linux
First, open the terminal Then enter the command
sudo gedit /etc/fonts/conf.d/49-sansserif.confSome people say to change the fourth line from the bottom “sans-serif”
to “WenQuanYi Zen Hei”, but this approach is not completely correct, because it will look inconsistent in different browsers.
For Firefox with default fonts, you can make this modification, but for Opera you need to change it to Bitstream Vera Serif for it to look harmonious. If you have changed the default font, you need to change it to your modified font.