This version of Unity is unsupported.
Method group is Obsolete

PrefabUtility.MergeAllPrefabInstances

Obsolete MergeAllPrefabInstances is deprecated. Prefabs are merged automatically. There is no need to call this method.

Declaration

public static void MergeAllPrefabInstances(Object targetObject);

Description

Force re-merging all Prefab instances of this Prefab.

This is done automatically and you will not have to call this function manually.