Discussion If you could re-write a book ending

[CultureGlitch]

Have you ever finished a book and sat there in disappointment or anger thinking "is this seriously how they decided to end the book/series?" I definitely have and it's honestly such a letdown. I remember reading a book when I was in grade 5 and it took me forever to read the book because I had a difficult time reading and once I finally got to the end of the book I was so disappointed and felt like I had wasted my entire time trying so hard to read a book that had a terrible ending. Unfortunately, I can't remember the title of the book but I do remember the feeling of feeling so discouraged to read.

So my question to you is: If you could re-write a book ending to any book what book would you want to re-write the ending to and what would you re-write the ending to be?
No spoilers in the open please! Use spoiler tags if you're going into details so it doesn't ruin it for someone who may want to read the book.