This is a checker required to run before upgrades on all long-running nodes.
NOTE: This script must be run on every node, it only checks the single current node, not the entire cluster.
On an operational Scylla node, with working nodetool available run
./scylla-check-gossiper-generation.sh
The output will advise on whether the user should get in touch with Scylla support before proceeding with an upgrade.