To reproduce: public RadForm1() { InitializeComponent(); this.radGridView1.EnableFiltering = true; this.radGridView1.ShowHeaderCellButtons = true; this.radGridView1.FilterPopupRequired += radGridView1_FilterPopupRequired; } private void radGridView1_FilterPopupRequired(object sender, Telerik.WinControls.UI.FilterPopupRequiredEventArgs e) { e.FilterPopup.PopupOpening -= FilterPopup_PopupOpening; e.FilterPopup.PopupOpening += FilterPopup_PopupOpening; } private void FilterPopup_PopupOpening(object sender, CancelEventArgs args) { args.Cancel = true; } Workaround: either set the ShowHeaderCellButtons property to false or closed the popup immediately after it is opened. private void radGridView1_FilterPopupRequired(object sender, Telerik.WinControls.UI.FilterPopupRequiredEventArgs e) { e.FilterPopup.PopupOpening -= FilterPopup_PopupOpening; e.FilterPopup.PopupOpening += FilterPopup_PopupOpening; } private void FilterPopup_PopupOpening(object sender, CancelEventArgs args) { RadListFilterPopup popup = sender as RadListFilterPopup; popup.PopupOpened -= popup_PopupOpened; popup.PopupOpened += popup_PopupOpened; } private void popup_PopupOpened(object sender, EventArgs args) { RadListFilterPopup popup = sender as RadListFilterPopup; popup.ClosePopup(RadPopupCloseReason.Mouse); }