Custom items (e.g., UserParameters) often take longer than the default Zabbix agent timeout. When execution exceeds the agent’s 3-second default, the item is marked not supported and you may see:

$ zabbix_get -s 10.0.0.61 -p 10050 -k "login_user"
ZBX_NOTSUPPORTED: Unsupported item key.

Increase the agent-side timeout too accommodate the slowest expected run time of your custom check.

• Edit the Zabbix agent configuration file (path may vary by distribution):

sudo vi /etc/zabbix/zabbix_agent.conf
# or: /etc/zabbix/zabbix_agentd.conf

• Set a higher timeout (valid range is 1–30 seconds). For example:

# Range: 1-30
Timeout=8

• Restart the agent to apply the change:

sudo systemctl restart zabbix-agent
# or on SysV init systems:
sudo /etc/init.d/zabbix-agent restart

• Re-test the item:

$ zabbix_get -s 10.0.0.61 -p 10050 -k "login_user"

Choose a timeout value that reliably covers the worst-case execution time of your custom item, without exceeding the maximum allowed by the agent.