6.0 was probably the biggest update yet, which requires some changes. You can read all of those on our MC-Market post here, in case you're updating between preview versions. In case you waited for the stable version, here are some info:
Update process
Execute /ps admin update in order to update PlayerServerCore
Add following three blocks to your config.yml file
player-limiting:# Should we use permissions for max-players management? If set to true, your# players should have playerserver.players.<amount>. The max amount of players# that you could give to a single server is 100000. You can also give them# playerserver.players.unlimited - for unlimited players. If the player# has no permission, he'll be able to have unlimited players.use-permissions:false# What is the max players each server should have?max-players-per-server:20
build-tools:# Should we log build-tools console output? Highly recommended to set# to true, as it will help me a lot with potential issues.build-tools-debug:true# What version should we build for PlayerServers?# Do "latest" for latest, do "1.8.8" for 1.8.8, etc.# If you want to change the sub-servers version,# you will have to delete templates/Spigot.jar first,# and than reboot the server. Btw, it is highly# recommended to use 1.8.8 for sub-servers.build-version:"1.8.8"
plugin-limiting:# Should we use permissions for max-plugins management? If set to true, your# players should have playerserver.plugins.<amount>. The max amount of plugins# that you could give to a single server is 20000. You can also give them# playerserver.plugins.unlimited - for unlimited plugins. If the player# has no permission, he'll be able to have unlimited players.## NOTE: If you use permissions, and you change player's permissions,# their server will need to reboot in order for changes to take place.use-permissions:false# What is the max players each server should have?max-plugins-per-server:20