GIMP could not open a .xcf on a different partition of same disk

On my Ubuntu Bionic: Ubuntu 18.04 LTS “Bionic Beaver” - Alpha amd64 (20180308)
corrado@corrado-p8-bb-0308:~$ inxi -SCGx
System: Host: corrado-p8-bb-0308 Kernel: 4.15.0-10-generic x86_64 bits: 64 gcc: 7.3.0
Desktop: Gnome 3.27.92 (Gtk 3.22.28-1ubuntu3) Distro: Ubuntu Bionic Beaver (development branch)
CPU: Dual core Intel Core i3-7100 (-MT-MCP-) arch: Skylake rev.9 cache: 3072 KB
flags: (lm nx sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx) bmips: 15648
clock speeds: max: 3900 MHz 1: 800 MHz 2: 800 MHz 3: 800 MHz 4: 800 MHz
Graphics: Card: Intel HD Graphics 630 bus-ID: 00:02.0
Display Server: x11 (X.Org 1.19.6 ) driver: i915 Resolution: 1920x1080@60.00hz
OpenGL: renderer: Mesa DRI Intel HD Graphics 630 (Kaby Lake GT2)
version: 4.5 Mesa 18.0.0-rc4 Direct Render: Yes

I installed GIMP 2.8.22 30 snapcrafters

corrado@corrado-p8-bb-0308:~$ snap list
Name Version Rev Developer Notes
core 16-2.31.1 4110 canonical core
gimp 2.8.22 30 snapcrafters -
gnome-3-26-1604 3.26.0 31 canonical -
gnome-calculator 3.26.0 75 canonical -
gnome-characters 3.26.2 50 canonical -
gnome-logs 3.26.2 23 canonical -
gnome-system-monitor 3.26.0 31 canonical -

I have no problems with .xcf on system partition but
trying to open a .xcf on a different partition of same disk I have a message:

GIMP Message
Opening ‘/media/corrado/dati1/GimpSnap/blu.xcf’ failed: Could not open ‘/media/corrado/dati1/GimpSnap/blu.xcf’ for reading: Permission denied

the same .xcf is correctly opened and updated using GIMP 2.8.20-2 (non snap)

Trying to document the problem with ubuntu-bug I have a window that says:
The crashed program seems to use third-part or local libraries:

Partition on my disk are as follows:
corrado@corrado-p8-bb-0308:~$ df -h
Filesystem Size Used Avail Use% Mounted on
udev 3,8G 0 3,8G 0% /dev
tmpfs 769M 1,9M 767M 1% /run
/dev/sda8 32G 5,2G 25G 18% /
tmpfs 3,8G 50M 3,8G 2% /dev/shm
tmpfs 5,0M 4,0K 5,0M 1% /run/lock
tmpfs 3,8G 0 3,8G 0% /sys/fs/cgroup
/dev/loop3 130M 130M 0 100% /snap/gnome-3-26-1604/27
/dev/loop2 13M 13M 0 100% /snap/gnome-characters/50
/dev/loop4 82M 82M 0 100% /snap/core/4110
/dev/loop1 1,7M 1,7M 0 100% /snap/gnome-calculator/75
/dev/loop5 3,4M 3,4M 0 100% /snap/gnome-system-monitor/31
/dev/loop0 21M 21M 0 100% /snap/gnome-logs/23
/dev/sda1 253M 4,6M 248M 2% /boot/efi
tmpfs 769M 16K 769M 1% /run/user/119
tmpfs 769M 92K 768M 1% /run/user/1000
/dev/sda10 251G 45G 194G 19% /media/corrado/dati1
/dev/sda12 184G 84G 91G 49% /media/corrado/dati3
/dev/sda5 32G 8,8G 21G 30% /media/corrado/p5-artful
/dev/loop6 146M 146M 0 100% /snap/gnome-3-26-1604/31
/dev/loop7 136M 136M 0 100% /snap/gimp/30
/dev/sda7 32G 8,7G 21G 30% /media/corrado/p7-bb-0305
corrado@corrado-p8-bb-0308:~$ sudo lsblk -o NAME,LABEL,SIZE,FSTYPE,UUID,MOUNTPOINT
[sudo] password for corrado:
loop0 20,9M squashfs /snap/gnome-logs/23
loop1 1,6M squashfs /snap/gnome-calculator/75
loop2 12,2M squashfs /snap/gnome-characters/50
loop3 129,3M squashfs /snap/gnome-3-26-1604/27
loop4 81,6M squashfs /snap/core/4110
loop5 3,3M squashfs /snap/gnome-system-monitor/31
loop6 145,3M squashfs /snap/gnome-3-26-1604/31
loop7 135,5M squashfs /snap/gimp/30
sda 931,5G
├─sda1 256M vfat 07D0-8A63 /boot/efi
├─sda2 8G swap c86a81fa-1d97-483c-99f8-318382983ed7 [SWAP]
├─sda3 p3-bb-0214-np 32G ext4 aac280a1-9957-4900-815c-e2c8e9191bf5
├─sda4 p4-xenial 32G ext4 fb5dda68-061f-4076-b0a8-22eac04841ae
├─sda5 p5-artful 32G ext4 79716554-248b-4337-a27b-a7f285dd5e09 /media/corrado/p5-artful
├─sda6 p6-bb-0301 32G ext4 56256adf-17be-4f5f-9946-e43fd7c6135e
├─sda7 p7-bb-0305 32G ext4 9a36b498-59f5-4a36-81db-3046ff6bdeaa /media/corrado/p7-bb-0305
├─sda8 p8-bb-0308 32G ext4 471da3b7-a266-4bf4-b2eb-c94a05ca83b8 /
├─sda9 p9-bb-0214+p 32G ext4 9d835052-a250-44f4-ba48-3f69768a80c7
├─sda10 dati1 256G ext4 dc880632-1403-4f5e-9c42-52b41bbe1b06 /media/corrado/dati1
├─sda11 dati2 256G ext4 b10bc991-9463-4010-be04-186d562d96dc
└─sda12 dati3 187,3G ext4 d7404e13-a307-4771-a1ec-1123cf5c85b2 /media/corrado/dati3
sr0 1024M

Thank’s for the attention

You should connect the ‘removable-media’ interface. Eg:

$ sudo snap connect gimp:removable-media

AIUI, soon this will be discoverable via gnome-software and you’ll be able to connect interfaces via a GUI.

splendido! thanks a lot