When checking your server for upgrade blockers, you receive the following warning:
WARN] *** Elevation Blocker detected: ***
Your machine has multiple network interface cards (NICs) using kernel-names (ethX).
Since the upgrade process cannot guarantee their stability after upgrading, you cannot upgrade.
The ELevate script is based on a tool named "leapp" which performs the upgrade of your operating system to the next major version. This core tool is unable to guarantee network stability in cases where a server has multiple network interface devices that share the name "eth."
Many servers will have a single network interface, which is the configuration that cPanel supports. You can verify this by looking at the networking configuration. A server with more than one device named "eth" will have problems with the ELevate script:
# ifconfig | grep eth[0-9]
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
eth1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
There are two ways to work around this issue. In some cases, a second interface may not be required and can be disabled. However, if they cannot be disabled, then all of the configured network interfaces must be renamed to something other than "eth[0-9]." In any case of multiple networking devices, none can be named "eth," or it will be blocked from the upgrade.
Editing the network configuration of a remote server is a potentially dangerous operation that, when done improperly, can prevent you from accessing your server.
The cPanel and WHM software do not have any way to manage your server's network configuration directly. We recommend working with a qualified System Administrator or your server's hosting provider to ensure the network configuration is updated safely.