Every time i go on a server it says invalid session error

whenever i try to join an online server of minecraft, i get an 'invalid session' error. i've been trying to fix this for 2 hours now and absolutely nothing is working. i'm using a macbook pro. i've tried changing my passcode, logging in and logging out, restarting the launcher multiple times, and restarting my computer and trying several different wifis. 

 

Hannah O made this and im experiencing the same things