I am running an old [release 1.22.6] version of mediawiki which I am finally being forced to upgrade or replace. I am considering creating a new subdomain using the 1.32.0 release of mediawiki. And then I intend to restore a backup of my old version databases and image files to the new version.
My main concern is about database changes between the versions. Will the backups be compatible with the new wiki version?
I also have the same concern about my modified LocalSettings.php file.
My mysql server version is 5.7.25
The database can be migrated to the new version, as described in the upgrading manual. The one somewhat-exception is the pageview data, check out the documentation for the HitCounters extension if you want to keep that.
LocalSettings.php might need to be updated, check the release logs or the documentation for the configuration variables you are modifying. It really depends on what you have in it.