Version: 2018.2
public static bool isUpdating ;

Description

True if the Editor is currently refreshing the AssetDatabase.

During AssetDatabase refreshing time, the editor checks to see if any files have changed, whether they need to be reimported, and reimports them. The isUpdating property will return true or false depending on whether the AssetDatabase is being loaded or not. (Read Only)

using UnityEditor;

public class NewSceneWhileNotUpdating { // Simple editor Script that lets you create a new // scene if editor is not updating.

[MenuItem("Example/New Scene while not updating")] static void EditorPlaying() { if (!EditorApplication.isUpdating) { EditorApplication.NewScene(); } } }