Request, params:

Result:

        "code": -32602,
        "message": "Invalid params.",
        "data": "Missing items for graph \"\"."

But documentation doesn't require that: http://www.zabbix.com/documentation/2.0/manual/appendix/api/graph/update

It is working fine with frontend version 2.0.0

Broken in revision 28084 ZBX-4861 fixed excess queries upon no-change graph saving