This cpanel ftp problem is usually caused when there is something wrong with files ownership, this happened to me today while I was trying to delete some files from a cPanel account using FileZilla, It even happened while I was trying to use cPanel file manager, there is an easy and quick way to fix this permission problem.
If you have a VPS or Dedicated server and have access to SSH, then ssh to your server and cd to the public_html directory of the user who’s having the problem
then run the following command to fix the permission problem
replace username with the actual cPanel username
and if you are on a shared hosting and don’t have SSH access, you might want to refer your hosting company to this page