btnx daemon will sometimes not work

[Matze1224]

I've get following error when starting btnx:

$ sudo /etc/init.d/btnx start
Starting btnx : Button Extension - mouse button rerouter daemon
 btnx: uinput modprobed successfully.
 btnx: Opening config file: /etc/btnx/btnx_config_G502
 btnx: No configured mouse handler detected: No such file or directory
 btnx: Looped through all configurations. Stopping.
 btnx: Configuration file error.
btnx failed to start (error code 150)

It occurs all times, like starting btnx directly or using systemd. The funny thing is, it will work the next reboot, and the reboot after, the same result will happen.

Using debian testing. Just noticed it this week, worked fine before (but I commonly use hibernation to disk instead of shutdowns).

[McThumpenstein]

Duplicated on Ubuntu 18.04.

btnx: No configured mouse handler detected: No such file or directory
 btnx: Looped through all configurations. Stopping.
 btnx: Configuration file error.
 btnx failed to start (error code 150)
 btnx.service: Control process exited, code=exited status=150
 btnx.service: Failed with result 'exit-code'.
 Failed to start LSB: Mouse button rerouter daemon..
-- Subject: Unit btnx.service has failed
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
-- 
-- Unit btnx.service has `failed.

Config file exists, restoring a backup via the btnx-config doesn't help.