hard drive space

I am trying to copy some folders/files to my second hard drive but keep getting a message that "there is not enough free disk space", although there is over 400GB free.

Any ideas to help will be appreciated.

Thank you.

How is the destination drive formatted? NTFS or FAT32 or what?

Do any of the folders have an exceptionally large number of files and/or sub-folders?

Have you tried copying just one folder to see what happens?

Just some initial thoughts