FTPMonitor / Guides / Authentication failed

Authentication failed

Why FTP/SFTP authentication fails and how to correct credential, key, and account policy issues.

Diagnose this automatically

Verify whether authentication is the actual failure point.

terminal
npx ftpmonitor check --protocol sftp --host example.com --port 22 --username user --password pass
Shareable output
terminal
npx ftpmonitor check --protocol sftp --host example.com --port 22 --username user --password pass --format slack --copy

Prefer the browser? Run the same check on the homepage.

Authentication failures mean the server rejected your login attempt.

This can be wrong credentials, wrong protocol, key issues, or account restrictions like IP allowlists.

Common causes

  • Wrong username/password (hidden whitespace is common)
  • Account locked/disabled/expired
  • Server requires FTPS instead of FTP (or disallows plain FTP)
  • SFTP key auth required or wrong key/passphrase
  • IP allowlist / geo restrictions

Fix checklist

  1. Copy/paste credentials carefully and retry (watch trailing spaces).
  2. Confirm which protocol is required: FTP vs FTPS vs SFTP.
  3. If SFTP key auth is required, confirm the private key + passphrase and that the public key is installed server-side.
  4. Ask the server owner if there’s an IP allowlist restriction.
Related
  • FTP 530 Login incorrect — How to fix FTP 530 errors: bad credentials, account restrictions, FTPS requirements, and permission issues.
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