Before you begin, if you are uncomfortable with a command line, you can do all the following steps using SourceTree, GitExtension, GitHub Desktop, or your favorite tool.
To solve the issue, you might have two scenarios:
1) Fix only remote repository branch which is behind commit
Example: Both branches are on the remote side
ahead === Master branch
behind === Develop branch
Solution:
Clone the repository to the local workspace: this will give you the Master branch which is ahead with commit
git clone repositoryUrl
Create a branch with Develop name and checkout to that branch locally
git checkout -b DevelopBranchName // this command creates and checkout the branch
Pull from the remote Develop branch. Conflict might occur. if so, fix the conflict and commit the changes.
git pull origin DevelopBranchName
Merge the local Develop branch with the remote Develop branch
git merge origin develop
Push the merged branch to the remote Develop branch
git push origin develop
2) Local Master branch is behind the remote Master branch
This means every locally created branch is behind.
Before preceding, you have to commit or stash all the changes you made on the branch that is behind commits.
Solution:
Checkout your local Master branch
git checkout master
Pull from remote Master branch
git pull origin master
Now your local Master is in sync with the remote Branch but other local branches, that branched from the local Master branch, are not in sync with your local Master branch because of the above command. To fix that:
Checkout the branch that is behind your local Master branch
git checkout BranchNameBehindCommit
Merge with the local Master branch
git merge master // Now your branch is in sync with local Master branch
If this branch is on the remote repository, you have to push your changes
git push origin branchBehindCommit