The plugin needs to store the UUIDs of the players on the sign somewhere, and previously that was done using a hover text (which isn't visible on signs).
Now it will use a newer Bukkit method (PersitantData).
The old format is still read by the plugin, so stored player UUIDs will carry over fine without a new lookup.
Old signs are converted whenever someone interacts with a protection
Eventually the plugin will stop reading the old format, so please upgrade this plugin so that everything can be converted in time.
Added support for SimpleClans - you can now add SimpleClans groups to your chests.
Added support for Minecraft 1.17.
The plugin uses some internal Minecraft classes, which were shifted around. So an update was necessary.
The internal classes are only necessary for reading signs in the old format, so at some point in the future this hacking around with Minecraft sign internals will be gone.
Still compatible with Minecraft 1.14 - 1.16.
Fixed being able to connect to someone else's container when connectContainers was on in the config file.