Recently found out that the plugin failed to start on server version 1.11.2 and older. This issue was due to some changes I made for 1.11.0, which I didn't test on older server versions.

This issue is now fixed with this update. (Yes, I did test it this time!)
The plugin is also tested and confirmed to work fully on 1.20.1.

Changelogs:

• Re-added the legacy methods to manage player data for server versions below 1.12
  • The legacy methods are not optimized for reading and writing files, and so may cause issues during startup and shutdown
  • Support will not be provided for issues caused by above
  • The plugin will warn you about above on startup when it uses the legacy methods
• Changed the text builder for listing blocked players or multiple possible targets to also work on server versions below 1.12
• Fixed plugin throwing an exception when attempting to get a player's inventory contents on 1.8.8... again
  • It was actually one line I missed when I fixed this issue in 1.11.0