Key Mismatch Login Failures

If the History log or User Activity log shows Login failure entries with "Key mismatch" as the failure type, the entry records a login attempt using an SFTP (SSH) key not found in your site.

This message can indicate either a legitimate mistake or a false alarm.

A user might be trying to log in using an incorrect SFTP (SSH) key. Contact the user and verify that the key being used matches an existing key in your Files.com site.

Many SFTP apps automatically attempt to log in using all their known SFTP (SSH) keys before presenting the user with a login prompt. These apps use a known_hosts file to store keys. If the known_hosts file contains multiple keys, the SFTP app cycles through them one by one, trying each one before falling back to a login prompt.

These automatic attempts trigger corresponding login failure entries in the log files, even though the user then logs in successfully. The log entries are accurate, and the failures themselves are not a problem.

You can contact the user and ask them to update their known_hosts file to remove unneeded keys. The file is shared by multiple SFTP and SSH apps, so removing keys is not always practical when several SFTP and SSH sites are actively used.