Upgraded from 6.2.4 to 6.2.7.
Result of db.odbc.get from oracle db:

[{
"MONITORNAME": "Create_Autodiscover",
"CRITICAL": null
}, {
"MONITORNAME": "Extract_generic_data_w33",
"CRITICAL": null
}]

jsonpath:

$[?(@.MONITORNAME=="Create_Autodiscover")].CRITICAL

Return:

[null]

But it should be just an empty array:

[]

Not sure, but it seems changed after ZBXNEXT-8040 or ZBXNEXT-8009

Also similar problem.
Data from odbc:

[{
"NAME": "versus",
"REPORT_NAME": null,
"SEVERITY": "major",
"NOT_GENERATED": "0",
"CONTENT_SEND_ERROR": "0",
"INFRA_SEND_ERROR": null,
"SENDING_HALTED": "0",
"NGC_JOB_HALTED": "0"
}, {
"NAME": "mansion",
"REPORT_NAME": null,
"SEVERITY": "critical",
"NOT_GENERATED": "0",
"CONTENT_SEND_ERROR": "0",
"INFRA_SEND_ERROR": "0",
"SENDING_HALTED": "0",
"NGC_JOB_HALTED": "0"
}]

jsonpath:

$[?(@.NAME=="versus" && @.SEVERITY=="major" && (@.NOT_GENERATED>0 || @.CONTENT_SEND_ERROR>0 || @.INFRA_SEND_ERROR>0 || @.SENDING_HALTED>0 || @.NGC_JOB_HALTED>0))]

Result:

[{
"CONTENT_SEND_ERROR": "0",
"CASINO_NAME": "versus",
"INFRA_SEND_ERROR": null,
"NGC_JOB_HALTED": "0",
"SENDING_HALTED": "0",
"REPORT_NAME": null,
"NOT_GENERATED": "0",
"SEVERITY": "major"
}]

Why "INFRA_SEND_ERROR": null more then 0?
Null not integer.

I have the same exact problem with a backuppc monitored host and upgraded zabbix from version 1:6.0.5-1+debian11 up to version 1:6.0.13-1+debian11.
My scenario does not include a zabbix proxy, i am directly using an agent2

On version's from 6.2 branch, i've the same error. 

For more info on my issue please check out this issue I opened on a zabbix template github.

https://github.com/yurtesen/zabbix_backuppc/issues/8

Same problem here.

I've tried to add a preprocessing step (on first place) who replace null with 0

But value is not changed. Perhaps I've made a mistake

Same Problem here, updating from 6.0.6 to anything newer breaks some custom templates. The triggers are firing, because the JSONPath return "null", not nothing.

No ETA for this issue? Thanks...

The null value comparison in jsonpath expression is going to be fixed here. null value is less than all other value types.

The null value returned as 'null' rather than empty string '' seems to be universal approach going by multiple online jsonpath testers I checked. Either way it's ambiguous result - after returning as string there is no way to tell if the original value was null or 'null' or '' whatever approach is chosen.

Possible workarounds for the original issue:

• Change trigger to check for null string - last(/BackupPC/backuppc.host[ {#HOST}

  ,error])<>"null"

• Add 'matches regular expression' preprocessing step to check for null with 'on fail' set to ''.

Of course with this real errors containing string 'null' would be ignored, but is is likely to have such error? That depends on the application.

Released ZBX-22130 in:

• pre-6.0.27rc1 91bfae6d21b
• pre-6.4.12rc1 9424b9788cc
• pre-7.0.0beta2 ff9594ab0c6