The error is shown when connecting to a server via FTP:
CONFIG_TEXT: The server's certificate is unknown. Please carefully examine the certificate to make sure the server can be trusted.
Valid from: xx/xx/xxxx
Valid to: xx/xx/xxxx - Certificate expired!
Plesk uses expired certificate. The certificate that is used for securing Plesk is also used for FTPS connections to the server. So, to protect FTP connections, a non-expired certificate for Plesk panel should be installed.
2. Create a new certificate to protect Plesk:
create Let's Encrypt certificate
1. go to Tools & Settings > SSL/TLS Certificates and click +Let's Encrypt button.
2. follow the steps from the article How to secure Plesk login page with SSL certificate to create a new certificate.
create self-signed certificate
- Open Tools & Settings > SSL/TLS Certificates > Add
- Fill in the necessary information.
- Click on Self-Signed.
- In Certificate for securing Plesk click Change and select the new certificate.