ContentPlaceHolder Confirm Dialog Box
The ContentPlaceHolder Confirm dialog box is displayed for different purposes. The dialog box is displayed in the following ways:
If you delete a ContentPlaceHolder control from a master page in Design view, the following version of the dialog box is displayed:
If you right-click a ContentPlaceHolder control on an ASP.NET page in Design view and select Default to Master's Content from the content menu, the following version of the dialog box is displayed:
If you remove this region, you will break any attached pages that provide custom content for it. Do you want to continue?
If the master page is used by an ASP.NET page, deleting the ContentPlaceHolder removes the connection between that ContentPlaceHolder control on the master page and the corresponding Content control on the ASP.NET page. Click Yes to remove the content from the master page from the ASP.NET page.
If you default to the Master Page content, everything in this region will be removed from the page. Do you want to continue?
Click Yes to remove any changes you made on the ASP.NET page inside the placeholder.