mqtt-explorer only works once

[JeffFaer]

$ cat /etc/lsb-release 
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=20.04
DISTRIB_CODENAME=focal
DISTRIB_DESCRIPTION="Ubuntu 20.04.4 LTS"
$ snap remove mqtt-explorer
$ snap install mqtt-explorer
$ which mqtt-explorer
/snap/bin/mqtt-explorer
$ mqtt-explorer
.
.
.
17:21:19.618 › App starting...
.
.
.
$ mqtt-explorer
$ echo $?
1

On a fresh install, I'm able to run mqtt-explorer exactly once. After the window closes and the command exits, any subsequent attempt to run mqtt-explorer exits immediately without logging anything and returns 1.

[knight-of-ni]

I ran into this same issue. In my case, it was due to using symlinks in my home folder for common directories like Downloads and Music. It seems this is a known issue with Electron snaps:
https://forum.snapcraft.io/t/some-snaps-will-only-launch-the-first-time/18509/18

When executing mqtt-explorer, while at the same time montoring journalctl, an apparmor DENIED message appeared:

AVC apparmor="DENIED" operation="capable" profile="/usr/lib/snapd/snap-confine" pid=18763 comm="snap-confine" capability=4  capname="fsetid"

I suppose I could have traced down this denial then learned how to fix it. Instead, however, I commented out all lines in this file:
~/snap/mqtt-explorer/current/.config/user-dirs.dirs

mqtt-explorer starts normally every time now.

[JeffFaer]

Oh weird, that's probably the same issue I'm in. My Documents folder is a symlink