Minecraft : tried to join with an invalid session или Failed to verify username! Решение

Проблема:

[20:19:46] [User Authenticator #2/INFO]: Disconnecting /192.168.168.1:49349: Failed to verify username!

[20:19:46] [User Authenticator #2/ERROR]: Username 'NANANA' tried to join with an invalid session

Решение:

В файле server.properties ищем строку online-mode=true и меняем на  online-mode=false