Why can't copy file to external harddisk even with a lot of space?

your harddisk still got tons of space
but you are trying to copy a large file
it shows a error message
"The file is too large for the destination file system"
usually this happened when u trying to copy a ISO file or full HD movie file
maybe u have to check your harddisk
see the format type is NTFS or FAT32
FAT32 format type is only allowed max file size with 4gb
if a single file that is larger than 4gb
it cannot be copy to the FAT32 harddisk

while if is NTFS harddisk,
the maximum allowed file size is unlimited