GIT: How to undo merge?

Question

I've done merge some-branch into master, but gets confilcts. How to undo this ?

git checkout master
git merge some-branch
...
CONFLICTS :(

Answer 1

git merge --abort

is a recently added option. It does what you expect.

Answer 2

If you have conflicts, your merge will not be committed yet so you can use git reset --hard HEAD to remove the merge.

Answer 3

With modern git, you can, as suggested in previous answer:

git merge --abort

Older syntax:

git reset --merge

Old-school, also suggested in previous answer:

git reset --hard

But actually, it is worth noticing that git merge --abort is only equivalent to git reset --merge given that MERGE_HEAD is present. This can be read in the git help for merge command.

git merge --abort is equivalent to git reset --merge when MERGE_HEAD is present.

After a failed merge, when there is no MERGE_HEAD, the failed merge can be undone with git reset --merge but not necessarily with git merge --abort, so they are not only old and new syntax for the same thing.

Personally I find git reset --merge more useful in everyday work so this is the method i use all the time.