I've been running MariaDB Galera Cluster for some time and only today realised that despite having identical versions of the MariaDB on all nodes, my versions of the Galera plugin are all different.
This seems to be the reason I am getting protocol errors like this during state transfer.
Only the patch versions are different. (ranging from 25.3.20 to 25.3.25).
Even more confusingly, when I run show global variables like 'wsrep_patch_version'; I get "wsrep_25.4" on all nodes.
I don't understand any of this, but it seems that although Galera is installed as a dependency when installing the MariaDB-server package, it is not also updated when updating MariaDB-server. At least not the minor version updates that I've been doing.
I am now in the situation where I need to update the Galera package on its own to fix these errors, but I'm not keen to do a rolling upgrade of MariaDB during a busy time.
So the questions is - Is it safe to upgrade to the latest version of the Galera package on its own without upgrading MariaDB itself? In other words is Galera 25.3.27 compatible with MariaDB 10.2.22? And will this likely fix my protocol errors?
