Unable to connect to Plesk server via secured FTP: Insecure server, it does not support FTP over TLS.

Symptoms

• The Allow only secure FTPS connections option is set at the Tools & Settings > Security Policy page.

• Connection via FTPS fails with one of the following errors (depends on FTP client):

  Insecure server, it does not support FTP over TLS.

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  534 Policy denies SSL

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  Local policy on server does not allow TLS secure connections

Cause

Settings for FTP site were manually changed in IIS.

Resolution

Note: This article can be applied only if you have administrator access to Plesk.

Contact a hosting provider if you do not have admin access to Plesk.

Reconfigure FTP site:

1. Log in to Plesk.

2. Go to Tools & Settings > Security Policy.

3. Set the Allow both secure FTPS and non-secure FTP connections option and press the Apply button.

4. Set the Allow only secure FTPS connections option back and press the OK button.