Vim loses undo history when changing buffers

Question

If I\'m working in a file, change to another buffer, and then change back, I have lost my undo history.

1. vim File1.txt - make a bunch of changes &

Answer 1

You can also add persistent undo, this will have vim store your undo even through restart:

" Persistent undo
set undofile
set undodir=$HOME/.vim/undo

set undolevels=1000
set undoreload=10000

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Edit - via @sanbor:

Don't forget to do mkdir ~/.vim/undo, otherwise vim won't do it for you.