Remmina - The GTK+ Remote Desktop Client  v1.4.33
Remmina is a remote desktop client written in GTK+, aiming to be useful for system administrators and travellers, who need to work with lots of remote computers in front of either large monitors or tiny netbooks. Remmina supports multiple network protocols in an integrated and consistent user interface. Currently RDP, VNC, NX, XDMCP and SSH are supported.
Squares-instead-of-text

Sometimes, when you start Remmina, it shows squares instead of each character in all of Remmina' GUI elements.

image

This is caused by a broken font cache.

The quick-fix is:

pkill remmina
rm -rf ~/.cache/fontconfig
fc-cache -f -v
sudo rm -rf /var/cache/fontconfig/*
sudo fc-cache -f -v

If you have a snap, you should add also these steps:

sudo rm -f /var/cache/fontconfig
rm -r ~/snap/remmina/common/.cache/fontconfig
rm -f ~/.cache/fontconfig/*

Start Remmina again and the problem should have disappeared.