Error Code 0x80028CA0 "type mismatch"

I have been trying backup my files to my WD Elements External Hard Drive and I keep getting the error code 0x80028CA0 “type mismatch” !!! Please someone help!! I have a ton of empty space on the drive and can’t get anything onto it!!

Usually happens when the “Libraries” folder is copied. No good solution, but some suggest backing up the contents of the folder and not the folder itself.