git error: failed to push some refs to remote

Try:

git push -f origin master

That should solve the problem.

Based on @Mehdi‘s comment, a clarification about —force pushing: The Git command above works safely only for the first commit. If there were already commits, pull requests or branches in previous, this resets all of it and set it from zero. If so, please refer @VonC‘s detailed answer for a better solution.

(Note: starting Oct. 2020, any new repository is created with the default branch main, not master. 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).

See "Why do I need to explicitly push a new branch?".

---

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.

I had the same problem. I was getting this problem because I had not made any commits, not even an initial commit and still I was trying to push.

Once I did git commit -m "your msg", everything worked fine.

If you just used git init and have added your files with git add . or something similar and have added your remote branch it might be that you just haven't committed (git commit -m 'commit message') anything locally to push to the remote... I just had this error and that was my issue.