Unable to open File Sharing menu: Error in cURL request: Unknown SSL protocol error in connection

Symptoms

• Unable to open the File Sharing menu in Plesk > Subscriptions > example.com with the error:

  PLESK_ERROR: Internal error: Error in cURL request: Unknown SSL protocol error in connection to 203.0.113.2:443

  ---

  PLESK_ERROR: Internal error: OK

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  PLESK_ERROR: Internal error: Error in cURL request: OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to 203.0.113.2:443

Cause

The missing binding for 443 port of Default Web Site.

Resolution

1. Log into the server via RDP.
2. Go to Start > Windows System > Administrative Tools > Internet Information Services (IIS) Manager > Server_name > Sites > Default Web Site > Bindings:
3. Add the binding as shown below and press the OK button:
   
   
4. Log into Plesk.
5. Go to Tools and Settings > File Sharing and enable the Generate secure links to files and folders option.
6. Press the OK button to apply the changes.