Snap-store doesn't open on Ubuntu Studio Focal Fossa 20.04 (SOLVED)

I updated my Ubuntu Studio 2 days ago. Tried to launch Snap Store but it doesn’t open. Tried to install latest stable version and run in terminal and returns that message:

mkdir: cannot create directory ‘/run/user/0’: Permission denied
18:35:03:0846 GLib-GIO g_app_info_get_name: assertion ‘G_IS_APP_INFO (appinfo)’ failed
No protocol specified
Unable to init server: Could not connect: Connection refused
18:35:03:0850 Gtk cannot open display: :0.0

When I run snap version it returns:

snap 2.44.3+20.04
snapd 2.44.3+20.04
series 16
ubuntu 20.04
kernel 5.4.0-29-lowlatency

I reinstalled Ubuntu Studio from a flash drive and it seems working well. Apparently, from previous version of Ubuntu the update had some problems