Go to Edit -> Project Settings -> Physics
Click on the object selector for the Deafult Material field.

The following errors show up in the Console:
InvalidOperationException: Operation is not valid due to the current state of the object
System.Collections.Generic.Stack`1[System.Boolean].Pop ()
UnityEditor.EditorGUI.EndDisabledGroup () (at /Users/builduser/buildslave/unity/build/Editor/Mono/EditorGUI.cs:211)
UnityEditor.EditorGUI+DisabledGroupScope.CloseScope () (at /Users/builduser/buildslave/unity/build/Editor/Mono/EditorGUI.cs:197)
UnityEngine.GUI+Scope.Dispose ()
UnityEditor.Editor.DoDrawDefaultInspector (UnityEditor.SerializedObject obj) (at /Users/builduser/buildslave/unity/build/Editor/Mono/Inspector/Editor.cs:331)
UnityEditor.Editor.DoDrawDefaultInspector () (at /Users/builduser/buildslave/unity/build/Editor/Mono/Inspector/Editor.cs:342)
UnityEditor.Editor.DrawDefaultInspector () (at /Users/builduser/buildslave/unity/build/artifacts/generated/common/editor/EditorBindings.gen.cs:263)
UnityEditor.PhysicsManagerInspector.OnInspectorGUI () (at /Users/builduser/buildslave/unity/build/Editor/Mono/Inspector/PhysicsManagerInspector.cs:104)

InvalidOperationException: Operation is not valid due to the current state of the object
System.Collections.Stack.Peek () (at /Users/builduser/buildslave/mono-runtime-and-classlibs/build/mcs/class/corlib/System.Collections/Stack.cs:321)
UnityEngine.GUILayoutUtility.EndLayoutGroup ()
UnityEngine.GUILayout.EndVertical ()
UnityEditor.EditorGUILayout.EndVertical () (at /Users/builduser/buildslave/unity/build/Editor/Mono/EditorGUI.cs:6726)

Regression from Unity 5.2.0p1 (cd0778e591b3)