Pop-up message on iTunes saying "Your iCloud Music Library Session has expired" every time I open the app

Every time I open my iTunes on my MacBook Pro, a message pops up saying "Your iCloud Music Library Session has expired". I have attempted logging out of my account and then logging back in, logging out and restarting my computer and then logging back in, and clicking cancel. I have searched google but no one has any solutions other than what I have already tried. It is getting to be very irritating and I was wondering if there was a way to fix this.