Error 503: Unable to connect to a secure FTP in Marketing Cloud

The Marketing Cloud Enhanced FTP is used as storage to import and export files out of Salesforce Marketing Cloud.

If you see the error message below, there are a couple of things you can take to resolve it:

Response: 503 Invalid sequence of commands (AUTH SSL/TLS required prior to authentication).

Error: Could not connect to server

Add ‘sftp:// to the Host field address

1. Find the Host address field in your third-party FTP client.
2. Add “s” to the beginning of the ftp:// portion of the address, so that it reads “sftp://.”

Enter the port number in the Port field

1. Find the Port Number field in your third-party FTP site.
2. Enter 22.