Error message when server does not return JSON structure. If you do not like default message, you are welcome to define your own. let grid = new w2grid({ name : 'grid', msgNotJSON: 'Give me JSON!', columns: [ { field: 'recid', text: 'ID', size: '50px' }, { field: 'lname', text: 'Last Name', size: '30%' }, { field: 'fname', text: 'First Name', size: '30%' }, { field: 'email', text: 'Email', size: '40%' }, { field: 'sdate', text: 'Start Date', size: '120px' }, { field: 'sdate', text: 'End Date', size: '120px' } ] });