Error installing PyCharm on Ubuntu: 'cannot mount squashfs image using squashfs: exec: mount: executable file not found in $PATH

Question

I'm using Ubuntu 22.04. I got the error when try to install PyCharm using snap package. I also got:

error: system does not fully support snapd: cannot mount squashfs image using "squashfs": exec: "mount": executable file not found in $PATH ERROR: not connected to the gnome-3-38-2004 content interface.

When I open Firefox using the terminal.

or

update.go:85: cannot change mount namespace according to change mount (/var/lib/snapd/hostfs/boot /boot none bind,ro 0 0): permission denied error: system does not fully support snapd: cannot mount squashfs image using "squashfs": exec: "mount": executable file not found in $PATH ERROR: not connected to the gnome-42-2204 content interface.

When I open Discord.

I tried to export $PATH, but it didn't work.