Failed to open image view, java.lang.NullPointerException

Hello to you all,
This is a problem I never had before, today I was trying to open any of the bands of an image taken by Sentinel 2 and downloaded from Copernicus open hub but it gave me this problem.
I’m running SNAP 9.00
Any suggestions on how to solve the problem is welcome!

the problem solved itself closing the program and reopening it…
Does anyone know the reason of the error and how to avoid it in the future?

Null pointer exception in Java can have many causes. You should consult the messages.log.N files (accessible using the Help Menu). A couple older logs are saved, so you may still have the log with details of the error. The files are very verbose, so the best way to identify the source of an error is to compare a log corresponding to an error with one from a session that did not have the error.