Git 推送错误“您当前分支的提示落后于其远程对应分支”

Question

I don't know why I can't push a modified file to the forked github repository.

$ git checkout -b br_mahmood
Switched to a new branch 'br_mahmood'
$ git status
On branch br_mahmood
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)

        modified:   util/job_launching/stats/example_stats.yml

no changes added to commit (use "git add" and/or "git commit -a")
$ git add util/job_launching/stats/example_stats.yml
$ git commit -S -m "Fixing something"

You need a passphrase to unlock the secret key for
user: "mahmood <EMAIL>"
4096-bit RSA key, ID 162AF377, created 2020-09-17

[br_mahmood 0115ea6] Fixing regex for L2_BW
 1 file changed, 1 insertion(+), 1 deletion(-)
$ git push -u origin br_mahmood
To https://github.com/MY_NAME/REPO
 ! [rejected]        br_mahmood -> br_mahmood (non-fast-forward)
error: failed to push some refs to 'https://github.com/MY_NAME/REPO'
hint: Updates were rejected because the tip of your current branch is behind
hint: its remote counterpart. Integrate the remote changes (e.g.
hint: 'git pull ...') before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.

By running git push I even entered username and password. However, I don't know why it raises that error.

Answer 1

From the error log, we can see that the remote repository already has a branch named br_mahmood . It's not safe to create the local br_mahmood from the head at that time by git checkout -b br_mahmood . If that head belongs to another branch which diverges from the remote br_mahmood , the local br_mahmood is not mapping correctly. A better practice is to create br_mahmood from the updated origin/br_mahmood :

git fetch origin br_mahmood
git checkout -b br_mahmood origin/br_mahmood

The commands could still raise an error if some config values are not set properly. To avoid that error:

git fetch origin br_mahmood
git checkout -b br_mahmood FETCH_HEAD

To solve the error in the log, we could use git pull origin br_mahmood or git pull -r origin br_mahmood before a next push. But, if you created the local br_mahmood from a wrong commit at the beginning, doing so could mingle two branches which should not be.

To fix the error in your case, a safe solution is:

# reset the local "br_mahmood" to the head of the remote "br_mahmood"
git fetch origin br_mahmood
git reset FETCH_HEAD --hard

# apply the commit "0115ea6" onto to the updated "br_mahmood"
git cherry-pick 0115ea6 

# update "br_mahmood" to avoid the "non-fast-forward" push error,
# in case the remote "br_mahmood" has been updated by others
git pull origin -r br_mahmood

# push again
git push origin -u br_mahmood