8. The Death Of Chewbacca
The Vector Prime was the book that killed Chewbacca. Yes, they killed him. The book was at that point a significant event- hitting in the months taking after The Phantom Menace. It denoted the beginning of the New Jedi Order series, which recounted YuuzhanVong’s intrusion .The Vong sent a moon colliding with a planet and while he could save a number of the inhabitants and Anakin Solo, Chewie went down in the flames.It was so huge, that since Disney made it non-canon which they’ve not discussed.
7. C-3PO’s Silver Leg
J.J. Abrams gave C-3PO a great red arm in The Force Awakens. Fine. But it wasn’t fine, since Disney made a huge deal out of it, burning through six months bringing up a one-shot comic that would clarify it all, with the inevitable answer basically being he lost it and it was supplanted by another droid’s. Stunner.