According to https://www.zabbix.com/documentation/2.0/manual/appendix/api/webcheck/update the 'webcheck.update' function should only require the 'httptestid' property to be defined plus of course one or more other properties which are actually being updated - similar to the update functions of other object types.

With Zabbix 2.0.5 when trying to update the 'macros' field of a web scenario by calling 'webcheck.update' with the 'httptestid' and the new 'macros' value, I get the error 'Only characters are allowed.'.

But if I specify the web scenario's 'name', in addition to 'httptestid' and the new 'macros' value, the function works successfully.