And you can rename existing repository default branch from master to main .
The rest of this 2014 answer has been updated to use "main")

(The following assumes github.com itself is not down, as eri0o points out in the comments : see www.githubstatus.com to be sure)

If the GitHub repo has seen new commits pushed to it, while you were working locally, I would advise using:

git pull --rebase
git push

The full syntax is:

git pull --rebase origin main
git push origin main

With Git 2.6+ (Sept. 2015), after having done (once)

git config --global pull.rebase true
git config --global rebase.autoStash true

A simple git pull would be enough.
(Note: with Git 2.27 Q2 2020 , a merge.autostash is also available for your regular pull, without rebase)

That way, you would replay (the --rebase part) your local commits on top of the newly updated origin/main (or origin/yourBranch: git pull origin yourBranch).

See a more complete example in the chapter 6 Pull with rebase of the Git Pocket Book .

I would recommend a:

add and commit first

git push -u origin main

Or git 2.37 Q2 2022+

git config --global push.autoSetupRemote true
git push

That would establish a tracking relationship between your local main branch and its upstream branch.
After that, any future push for that branch can be done with a simple:

git push

Again, with Git 2.37+ and its global option push.autoSetupRemote , a simple git push even for the first one would do the same (I.e: establishing a tracking relationship between your local main branch and its upstream branch origin/main).

Since the OP already reset and redone its commit on top of origin/main:

git reset --mixed origin/main
git add .
git commit -m "This is a new commit for what I originally planned to be amended"
git push origin main

There is no need to pull --rebase.

Note: git reset --mixed origin/main can also be written git reset origin/main, since the --mixed option is the default one when using git reset .