How to move the backup file on my NAS from a folder to another one?

Hi, i've changed in the settings the folder for the "local storage for originals" ... and now i have a problem: only 5000 pictures on a total of more than 50000 moved to the new folder.

the new folder :

I have this prompt :

But after waiting many minutes, i have another prompt saying "impossible to move your photos" !!

Any ideas ?