When editing a sketch, you may see the text "Graphics controls disabled" near the bottom of the sketch area (blue background). This is not an error. This message means that the graphics controls (zoom, pan, rotate, etc.) have been deselected so that when you edit the sketch the viewport is not modified.
If, for example, the Rotate control was selected while you tried to drag and move a point, the viewport would rotate while you are dragging. Or, if the zoom tool was active, the view would zoom in each time you clicked, when the desired action was really to add/edit/remove a point on the sketch. To avoid this unintended behavior, the graphics controls are automatically disabled when opening the sketcher and the message is displayed to notify the user.