I recently ran into an issue where I could no longer FTP files to my Linux droplet when multiple users were uploading to the server. The server kept the user as the owner despite me adding them to the www-data group. This fix comes from my ex-boss, James Tomasino who was kind enough to provide some help since I was stumped. I'm sharing in case anyone else runs into the same issue and finds it useful. You'll need to fire up terminal, ssh to the server, and then execute these commands: