Custom media type - Error loading state file

[Wriswith]

I am running Zabbix on Ubuntu 18.04 for a while now. I installed Zabbix4.4 and recently updated to Zabbix 5.0.3. I am trying to set up alerting to the Signal messaging app through a script. I set up a media type script with the required parameters. When Zabbix calls the script I get the error below in zabbix server log. I have been searching for errors referencing "Error loading state file: /var/lib/zabbix", but I am coming up empty. I checked and there is no /var/lib/zabbix on my system.

Can anyone give me a clue on how to troubleshoot this issue?

11763:20200909:204842.292 Failed to execute command "/usr/lib/zabbix/alertscripts/alert_to_signal.sh '+3XXXXXXXXXXXX' 'Problem started at 20:48:16 on 2020.09.09
Problem name: disk_full
Host: SERVER1
Severity: High

Original problem ID: 117267
'": Error loading state file: /var/lib/zabbix

[Wriswith]

After some time I came back to this problem. I was able to find the cause of the issue.
There is a (2 second?) timeout on the alerting script. After this time the server throws this very non descriptive error (Error loading state file: /var/lib/zabbix).

I did not find any way to tweak this timeout. I instead added an '&' to the long running command in my bashscript to run it in the background. The downside of this workaround is that the zabbix server is no longer able to retry the script if it fails to send.