I bought the game recently, everytime I try to log into a server I get an Invalid Session error (picture attached), and when I enter a singleplayer world I don't have my skin.
I tried everything to fix it, including purging minecraft completely from my computer and reinstalling it (did it multiple times), logging off and logging in (multiple times), and contacting minecraft support (they told me to post a bug report here in the last message before suddenly closing the ticket with no resolution), I even tried logging into my account in a completely different PC and network at my friend's house (which he plays minecraft in his account no problem) and the error still persisted there.