Failed to update data via service

Hi all,

I have configured SAP Fiori transnational app ( approve purchase order ) but i don't know what step is missing. I am  getting following error in google chrome network tap, Please find the error snapshot.

Suggest me this error is frond ens error or back end error.

Frond End  : Netweaver 7.4

Back end   : Abap ehp7

DB            : SQL

Thanks in advance