According to this article Windows 10 should allow filepaths longer then 260 characters. I saved several documents with a long filepath in a previous installation (which was upgraded from Windows 7 and probably inherited some tweak to allow longer paths).
How can I allow filepaths longer then 260 characters in Windows 10 Home Edition?
[ Windows 10 Home Edition V. 1511 b. 10586.420 ]
I realized the long path was in the external hard-disk form which I was trying to copy the folder, I changed it there and I moved my files. Even then, I will leave the question for anyone who may be interested.