I plugged in a USB drive that already contains five episodes and has worked normally with many devices. It still shows about 50 GB of free space, but when I try to copy a movie that's around 4 GB, Windows says the file is too large for the destination file system. What's causing this, and what's the best way to fix it without losing the files already on the drive?
3 Answers
The drive is probably formatted as FAT32. FAT32 can store lots of data, but it has a maximum single-file size of roughly 4 GB, so free space doesn’t matter in this case. Back up the existing files, reformat the drive as exFAT or NTFS, then copy everything back. Reformatting will erase the drive.
Use exFAT for broad compatibility and support for large files. NTFS also removes the 4 GB limit, but some TVs, phones, consoles, and other devices may not be able to write to an NTFS drive. Make a backup first, format the USB, and restore the files afterward.
The other options are splitting the movie into smaller parts or converting the drive without formatting, if your operating system supports that safely. However, backing up the contents and formatting as exFAT is generally the simplest solution. FAT32 is mainly useful for older hardware that specifically requires it.

exFAT is usually the better choice if you want to use the USB with different computers and devices. NTFS is a good option when it will mainly be used with Windows.