FTPS connection fails in PhpStorm: vfs.provider.ftps/connect.error

Problem

1. Configure FTPS connection in Settings | Build, Execution, Deployment | Deployment.
2. Click the Test Connection button.

3. The error message is shown:

   Test FTPS Connection
   
   Connection to server_name failed.
   Unknown message with code
   "vfs.provider.ftps/connect.error".

Cause

The connection to the remote server failed. The IDE received the response; however, it was unable to interpret it and display a more informative error message.

Resolution

• Make sure that the login/password combination is correct.
• Verify that port 21 or 990 is used for the FTPS connection.
• If necessary, adjust the Settings | Build, Execution, Deployment | Deployment | Advanced | TLS setting.
• Depending on the remote host settings, it may also be necessary to enable Settings | Build, Execution, Deployment | Deployment | Connection | Advanced | Passive mode.