Hello!
Is it possible to fix it?
https://pastebin.com/Deb2nbur
In one hour there were 2 server crashes With this error.

ChestShop-authors/ChestShop-3#78
ProtocolSupport/ProtocolSupport#728

Try updating chestshop to a developer build (despite it can be dangerous, they have fixed some bugs that the latest stable buildd has)

Unfortunately PermissionsEx is currently unmaintained and no further updates are planned. Because of this, all pull requests are being closed. If you are looking for an actively maintained permissions plugin, take a look at LuckPerms. It is compatible with major server platforms and can import data from PEX.