Linux client not working

$ ./Outline-Client.AppImage
loading web app from file:///tmp/.mount_OutlinK6eLfr/resources/app.asar/www/electron_index.html?appName=Outline
(node:28847) electron: The default of contextIsolation is deprecated and will be changing from false to true in a future release of Electron.  See https://github.com/electron/electron/issues/23506 for more information
Could not load active tunnel:  [Error: ENOENT: no such file or directory, open '/home/user/.config/Outline/connection_store'] {
  errno: -2,
  code: 'ENOENT',
  syscall: 'open',
  path: '/home/user/.config/Outline/connection_store'
}
Checking for update
(electron) Sending uncompressed crash reports is deprecated and will be removed in a future version of Electron. Set { compress: true } to opt-in to the new behavior. Crash reports will be uploaded gzipped, which most crash reporting servers support.
Outline is starting
Update for version 1.4.0 is not available (latest version: 1.4.0, downgrade is disallowed).
connecting to 3f8039ae-83b8-41f7-bdc6-7cc561db272c...
(node:28847) [DEP0005] DeprecationWarning: Buffer() is deprecated due to security and usability issues. Please use the Buffer.alloc(), Buffer.allocUnsafe(), or Buffer.from() methods instead.
UDP support: true
(re-)installing routing daemon
copying service files to /tmp/rPVBsY
[EXIT - badvpn-tun2socks]: Exited with code 1
a helper has exited, disconnecting
could not stop routing: Cannot call write after a stream was destroyed
[EXIT - ss-local]: Exited with code 0
could not connect: h (routing daemon is not running)
Promise "DNS lookup" resolved before 10000 ms

[afaikiac]

I had the same bug. The problem appeared after a kernel update. It happens because there is no kernel module TUN. This can be checked with the following command:

$ sudo dmesg | grep TUN
[   26.091113] tun: Universal TUN/TAP device driver, 1.6

Outline needs to create a TUN interface to work properly.

$ route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.31.1    0.0.0.0         UG    304    0        0 wlan0
10.0.85.0       0.0.0.0         255.255.255.0   U     0      0        0 outline-tun0
192.168.31.0    0.0.0.0         255.255.255.0   U     0      0        0 wlan0

If you don’t get this output, simply reboot and check again.

If it is still missing, add a TUN kernel module and reboot.

sudo modprobe tun
lsmod | grep tun
reboot

I hope it helps.

[aaaamirabbas]

This problem exists in the following versions and I tested it.

Ubuntu 20.04 Ubuntu 21.10 Ubuntu 22.04 PopOS 22.04

Please fix this bug.