Recently I had to upgrade an install of MediaWiki from version 1.6.12 to the latest version. It was originally installed on a host that only had PHP4 and MySQL4. The 1.6.x versions of MediaWiki were the last to support PHP 4. We were moving the site to a new server with PHP5 and MySQL5 so it was time to upgrade to the latest release of MediaWiki, version 1.15.1.
I selected to use the new binary database format during install. After copying over the database and running the upgrade script I came across an interesting error:
Warning: you requested the mysql5-binary schema, but the existing database has the mysql4 schema. This upgrade script can’t convert it, so it will remain mysql4.
