Custom on failure → Set value: 0 not working (wrong value type error)

[GChmurka]

I have a simple item with type Numeric (unsigned) and the following key:

vfs.file.contents[/sys/block/md0/md/sync_speed]

The content of this file can be either a number or "none".

Despite setting preprocessing:


I still get the error:

Value of type "string" is not suitable for value type "Numeric (unsigned)". Value "none"

Is this the expected behavior in Zabbix?
I'm using version 7.0.8.

[cyber]

You are trying to save string value to numeric field... you are getting "none". It is not a error.
"Check for not supported value" would work, for example, if that file is not found any more.

Use "Replace" preprocessing to replace "none" with 0 and you should be fine. If there is a number, it will be passed on as "none" is not found, nothing is replaced.

[GChmurka]

Alright, I’ve learned that a 'not supported value' is a value that, for example, does not have a key in userprefs.
I found that the best way to ensure a value is always a number or gets discarded in Zabbix preprocessing is to use:

1. Multiply by 1 – this forces the value to be numeric (if it's not, it will cause an error).
2. Custom on fail → Discard value – if the operation fails (e.g., the value is text), Zabbix will discard it.