Hi, Comunity all!

I made Draw.io diagram on the first board, then copy to the second board and delete the first one.

Now I’m trying to open the diagram, but cannot open and shows the message “Not a diagram file (error on line 1 at column 1: Start tag expected, '<' not found)”

I restored the deleted diagram from board histroy, but show the same message.

How can I recover it? 

Wada