Addressing merge conflicts
If your changes have merge conflicts with the base branch, you must address the merge conflicts before you can merge your pull request's changes.
About merge conflicts
Merge conflicts happen when you merge branches that have competing commits, and Git needs your help to decide which changes to incorporate in the final merge.
Resolving a merge conflict on GitHub
You can resolve simple merge conflicts that involve competing line changes on GitHub, using the conflict editor.
Resolving a merge conflict using the command line
You can resolve merge conflicts using the command line and a text editor.