We have been using version 4.1.1 and are migrating to We have editor grids with buffered stores which contain large volume of data. The editor grids are similar to the row-editing example(except that it uses buffered store). But the add functionality for the grid has stopped after migration and it raises an error
Ext.Error: insert operation not supported into buffered Store.

HTML Code:
var rowEditing = Ext.create('Ext.grid.plugin.RowEditing', {
        clicksToMoveEditor: 1,
        autoCancel: false

    // create the grid and specify what field you want
    // to use for the editor at each column.
    var grid = Ext.create('Ext.grid.Panel', {
        store: store,
        columns: [{
            header: 'Name',
            dataIndex: 'name',
            flex: 1,
            editor: {
                // defaults to textfield if no xtype is supplied
                allowBlank: false
        }, {
            header: 'Email',
            dataIndex: 'email',
            width: 160,
            editor: {
                allowBlank: false,
                vtype: 'email'
        }, {
            xtype: 'datecolumn',
            header: 'Start Date',
            dataIndex: 'start',
            width: 90,
            editor: {
                xtype: 'datefield',
                allowBlank: false,
                format: 'm/d/Y',
                minValue: '01/01/2006',
                minText: 'Cannot have a start date before the company existed!',
                maxValue: Ext.Date.format(new Date(), 'm/d/Y')
        }, {
            xtype: 'numbercolumn',
            header: 'Salary',
            dataIndex: 'salary',
            format: '$0,0',
            width: 90,
            editor: {
                xtype: 'numberfield',
                allowBlank: false,
                minValue: 1,
                maxValue: 150000
        }, {
            xtype: 'checkcolumn',
            header: 'Active?',
            dataIndex: 'active',
            width: 60,
            editor: {
                xtype: 'checkbox',
                cls: 'x-grid-checkheader-editor'
        renderTo: 'editor-grid',
        width: 600,
        height: 400,
        title: 'Employee Salaries',
        frame: true,
        tbar: [{
            text: 'Add Employee',
            iconCls: 'employee-add',
            handler : function() {

                // Create a model instance
                var r = Ext.create('Employee', {
                    name: 'New Guy',
                    email: 'new@sencha-test.com',
                    start: Ext.Date.clearTime(new Date()),
                    salary: 50000,
                    active: true

                store.insert(0, r);
                rowEditing.startEdit(0, 0);
        plugins: [rowEditing],
Please advise on what is the approach to be followed.