Fast-forward merge is not possible. To merge this request, first rebase locally

I've suffered a lot from it, and today I found an EXTREMELY SIMPLE way:

For example, assuming you want to pass the content:

From a branch called feature/NativeSubmodule To a branch called develop .

Download and install SourceTree [ https://www.sourcetreeapp.com ], then open your project in it, and follow the steps in this image:

And then:

If you want to just Replace the destination branch(develop) with the Origin branch content(feature/NativeSubmodule), you just don't have to do the "Extra)" step. :D

In my case this happens when I send merge request without pulling and merging all new code from develop branch.

I just wrote this in console

git add .
git commit -m "my commit"
git push 

Without change branch to develop and pull (after merge) everything from it.

For work you need to pull actual code from develop and merge it to your branch

git add .
git commit -m "my commit"
git checkout develop
git pull
git checkout <branch_name>
git merge develop
// if have any  conflicts fix them and push it
git push  // or if need set upstream git push --set-upstream origin <branch_name>

Starting on your newBranch:

git checkout master to get back on the master branch

git pull origin master to get the most up-to-date version of the master branch

git checkout newBranch to get back on your newBranch

git rebase origin/master -i to perform an interactive rebase. The command will take you through and let you pick commits, rename them, squash them, etc. Assuming you will want to keep them all, it will pause when there are merge conflicts and then you'll have to resolve them in your text editor, it will tell you where (in your text editor) that the conflicts occur. You will have to add those files after fixing them then do git rebase --continue to proceed with the rebase.

When you're done with the rebase your newBranch will be synced up with master and have any commits in master that weren't there when you started your work, and all merge conflicts will be resolved so that you can easily merge your newBranch.

It seems that your GitLab is configured to not allow feature branches with merge commits to be merged into the master branch. This is where you took a wrong turn:

After that I committed my local changes and pulled the changes in newbranch to local branch.

What you should have done is to commit your work, and then pull via rebase from the remote newbranch branch. To remedy the situation, I suggest nuking the merge commit which happened when you pulled from GitLab. A merge commit is likely what happened, because git pull by default uses the merge strategy, not the rebase strategy. Check git log, and see how many commits were introduced due to the incorrect pull. Assuming there were only a single merge commit, then the following should do:

git reset --hard HEAD~1

Verify again that git log looks correct. You should now see only your latest commit on the top of the branch. Assuming you do see this, then you are good to pull via rebase:

git pull --rebase origin newbranch

This will bring in your colleague's commit, then replay your latest commit on top of the branch. Finally, you may push the branch out, and the problem should be resolved:

git push origin newbranch

Note that doing a hard reset as I have suggested above is generally not a good thing to do. But in your case, no one has seen that merge commit yet, because GitLab rejected your attempt to push. So you should be safe in removing it.