Unable to install Plesk license: cURL cannot communicate with license server

• License installation on a Plesk server fails:

  PLESK_ERROR: cURL cannot communicate with license server https://id-00.kaid.plesk.com:443/ (): Couldn't connect to server(7) cURL cannot communicate with license server https://id-00.kaid.plesk.com:443/ (): Couldn't resolve host name(6) (Error code: 2)

• The hostname id-00.kaid.plesk.com is correctly resolved over DNS while checking with commands:

  • For Linux:

    # host id-00.kaid.plesk.com
    id-00.kaid.plesk.com is an alias for ka.plesk.com.
    ka.plesk.com has address 195.214.233.82
    ka.plesk.com has address 195.214.233.80
    ka.plesk.com has address 195.214.233.81

  • For Windows:

    C:\> nslookup id-00.kaid.plesk.com
    Server:  UnKnown
    Address:  2620:0:28a9:4::1
    Non-authoritative answer:
    Name:    ka.plesk.com
    Addresses:  195.214.233.81
              195.214.233.80
              195.214.233.82
    Aliases:  id-00.kaid.plesk.com

• The connection to licensing servers fails:

  # telnet ka.plesk.com 443
  Trying 195.214.233.82...
  telnet: Unable to connect to remote host: Connection refused

• There are no blocking firewall rules for outbound traffic either in the local Firewall or in the external Firewall (if there is any)
• Other operations on the server related to outgoing traffic, for example, packages installation or extensions catalog opening, fail as well:

  • For Linux

    # apt install nmap -y
    ..........
    Err:1 http://archive.ubuntu.com/ubuntu xenial InRelease
    Could not connect to archive.ubuntu.com:80 (203.0.113.2), - connection timed out [IP: 203.0.113.2 80]
    ..........

    # wget https://ext.plesk.com
    --2024-07-09 22:43:42-- https://ext.plesk.com/
    Resolving ext.plesk.com (ext.plesk.com)... 79.127.235.11, 79.127.235.9, 79.127.213.245, ...
    Connecting to ext.plesk.com (ext.plesk.com)|79.127.235.11|:443... connected.
    WARNING: Could not save SSL session data for socket 3
    Failed writing HTTP request: The specified session has been invalidated for some reason..
    Retrying.
    ..........

  • For Windows:

    C:\> curl https://ext.plesk.com
    curl: (28) Failed to connect to ext.plesk.com port 443 after 21048 ms: Couldn't connect to server

Cause

Server-wide outgoing traffic issue. Most likely, issues on ISP/server provider side.

Resolution

Contact the ISP or server provider for further assistance.