cPanel service does not start after upgrade - EOL version of cPanel

Symptoms

After updating an EOL version of cPanel to cover the latest CVE-2026-41940, cPanel is failing to start with the following:

CONFIG_TEXT: Cpanel::Exception::IO::SocketOpenError/(XID 2rzw7x) The system failed to open a socket of domain “16” and type “SOCK_DGRAM” using the “ipv4” protocol because of an error: Address family not supported by protocol

Cause

cPanel uses the updated socket protocols as of later cPanel versions, and older kernels will not have this feature. As such, cPanel is unable to bind to its ports and fails to start.

Resolution

https://cpanel.zendesk.com/agent/tickets/95990551

1. Create the following file:

   # touch /var/cpanel/kernel_does_not_support_modern_ipv4_socket_options

2. Restart the cPanel service:

   # /scripts/restartsrv_cpsrvd