HeadsPlus does not function correctly on the latest Paper builds for 1.16.1 as of right now. As a result, custom head textures can not be applied, and the commands /head and /myhead have been disabled in this version to prevent damage that can be caused by this to your server. This is not HeadsPlus exclusive.

For more information, please read https://github.com/PaperMC/Paper/issues/3667

Once the issue is fixed, you can either revert back to v6.10.9 temporarily or wait for me to remove the warning.

So yes, I included a warning in the plugin about Paper and also hopefully fixed the updater thinking 6.10.8 was the latest version, dumb machine​