Error and crash

screenshot.PNG
Hello,
After I update the engine to 4.7.2 everytime I make some change and save the file the window above appears.
And when I hit YES and save and play the game in editor the engine crashed!
this happens every time and when I reopen the engine everything goes well until I make some change and save again.
Wil anyone tell me why this happens and how to solve it? thx:D

Check out this link: https://docs.unrealengine.com/latest/INT/Search/index.html?q=this+map+is+using+externally+referenced&x=0&y=0 - It pulls all the data from the forums, documentation, Answerhub and everywhere in between to find people similar with your issue you’re facing. Hopefully it helps!