Zabbix
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FAQ
ZBX_NOTSUPPORTED
Could be anything, enable logging on agent. It could be version mismatch. Check
zabbix_get -s yourhost -k agent.version
If that works, you're calling for an undefined or unsupported key.
Incorrect trigger expression. Host "xx" does not exist or you have no access to this host.
Means there's no related item.
zabbix_get returns nothing
best look at log on agent side