Here are some configuration items that have caused SFTP issues for some of our customers.

User Account Settings

Verify that the username is enabled, and that the username and password are correct. Edit the user and verify that the Account enabled setting is turned on. Verify that the Authentication method is not set to "none". (When set to "none", a user account can only authenticate by using an API key or an SSH/SFTP Key.)

SFTP Protocol Privileges

The user might have SFTP disabled in their settings. Edit the user and check that SFTP is enabled in their Privileges for Protocol access.

Require Password Change

If the user account has been configured to Require password change on next login then SFTP login will not succeed until the password has been changed. Ask the user to access Files.com using our web interface and have them complete the password change prior to attempting a login via SFTP.

Two Factor Authentication (2FA)

If the user has Two Factor Authentication (2FA) Enabled, only certain 2FA methods work with SFTP. The Two Factor Authentication documentation page has more information on this**.** Additionally, when using 2FA with SFTP, you need to disable any parallelism in your SFTP app, because 2FA is only valid for one connection at a time. (Elsewhere we suggest maxing out the available parallelism in your app for performance. 2FA is a case where this would not be available.)

IP Whitelist

If your site or user is subject to an IP whitelist, the user must access the site using one of the whitelisted IPs from either list. Check your IP whitelists to verify that the IP address that SFTP connections are being made from are allowed.

Eliminate SFTP as the Sole Cause

If a user is having problems logging in using SFTP then have them attempt to log in using the Files.com web interface. If the issue persists there then this eliminates SFTP as the cause.