AltDetector 2.0 drops using YAML flat files for data storage in favor of using a real database. This should be much better for larger servers or for owners with multiple servers who want to share the same MySQL database.

Upgrade instructions (see the Overview page for new installations):

If you have an existing installation of AltDetector, you can upgrade to the new jar file and the next time you start your server, it will automatically convert your old data to an SQLite database. You don't need to do anything else, and the plugin will work as usual with the new database. You can keep the old ipdata.yml file around as a backup, but it will no longer be used.

I recommend using the SQLite database. (Note that Spigot 1.8.8 ships with a very old version of SQLite which will not work with this plugin.)

If you want to use a MySQL database, first run the new version of AltDetector so it updates config.yml. Then edit config.yml and change database-type to mysql and fill out the mysql database credentials. jdbcurl-properties will be appended to the connection URL, so you can add any items that are required by your MySQL server. Finally, change convert-from to yml so your old data will be converted to the new MySQL database. Then restart your server.

If you're using multiple servers connecting to one MySQL database, you should pick one server to use the convert-from option, then let the other servers use the new database.