Why does Vim say "Already at newest change" despite a full "changes" history list?

Question

I seem to be unable to undo something in a file I saved, despite that the history of changes shows up with I press :changes. So the change history is known to vim but I cannot access it?

I thought it was possible to go back to previous changes even after you save the file, but perhaps I am wrong. I also the get the "Already at" message with g- and g+.

Answer 1

The change list is a different thing from the undo list.

The change list is a list of locations of changes, and it can be viewed with :changes and navigated with e.g. g; and g,.

The g+ and g- commands that you’re using move instead through the undo list. This is a tree of different file states: it’s what you are navigating when you undo and redo changes. The undo list can be viewed with :undolist.

Vim only persists the undo list between sessions when you have undo persistance switched on: it is switched off by default.

Try adding set undofile to your .vimrc or read the documentation at :help undo-persistence for full details.