It seems like there is not much information about FTP protocol errors. One that came up recently is “553 Error”.

553 Error is an FTP error which is associated with FTP configured limitations. Most of the times it can result in one of two cases:

1. Due to ‘directory structure too deep’. That means that you have folders inside of folders inside of folders in your root directory folder. For example: http://www.yourwebsite.com/folder1/folder2/f3/f4/f5/f6/filename.html

Some hosting providers limit how deep you can go and a violation of it will cause this error.

2. One other source of the error is ’553: Improper Names’. Hosting providers may configure the server to not allow specific names for files. That might be the use of characters that are usually allowed by the OS but they would like to avoid.

Due to various configuration options this error might come up for other reasons as well. You’ll do best to contact your hosting provider support