Please refer to JSON-RPC2.0 manual, error numbers are predefined. Error data field is for details.

so i guess we can't change the error code ?
is there anything to do for this issue ?

hmm. would be useful to list all error codes returned by zabbix api at this point in the api docs - even if that would partially duplicate json-rpc spec or whatever

Upon reading the JSON RPC 2.0 specification it is in fact possible for the application developer to define their own error codes.

http://groups.google.com/group/json-rpc/web/json-rpc-2-0

Section 5.1 has the following two key statements:
1) "The error codes from and including -32768 to -32000 are reserved for pre-defined errors. Any code within this range, but not defined explicitly below is reserved for future use. The error codes are nearly the same as those suggested for XML-RPC at the following url: http://xmlrpc-epi.sourceforge.net/specs/rfc.fault_codes.php"

2) "The remainder of the space is available for application defined errors."

Thus all error codes outside the range of -32,000 -> -32,768 are available for the end application, such as Zabbix.

this seems to be fairly important to make api messages reasonably parse-able - although a spec should be created before implementing anything, detailing decided upon return codes and guidelines/rules for assigning new ones

Agreed!

Let's create a page on Zabbix.org and start filling out the error code table. Also if one of us is feeling very "adventurous" we may even start submitting some patches for this.

If this can make it into Zabbix 2.0 then the API can be one step closer to "winning."

Any chance of a back port to the 1.8.x series?

+1 for this!

I think a good start would be to define ranges for different error codes. We have lots to choose from!

reportedly in case of invalid auth the error code could now be -32602 - but that does not seem to be documented anywhere, so probably best not to rely on it anyway

Please reopen if required.