Options grayed out on Coordinate System tab of the Data Frame Properties dialog box

Description

When trying to change the coordinate system of a Data Frame, all the coordinate choices, Favorites, Predefined, and Custom, are grayed out.

Cause

ArcMap is in Editing mode.

Solution or Workaround

Stop Editing the layer. Once you have stopped editing, you will be able to change the coordinate system of the Data Frame. See the article Stopping an edit session.