Required reviews ensure that pull requests have at least one approved review before collaborators can make changes to a protected branch.
Repository administrators can require that all pull requests receive at least one approved review from someone with write or admin permissions before they're merged into the default branch. For more information, see "About protected branches."
When required reviews are enabled, anyone with access to the repository can approve changes in a pull request. However, to merge your pull request you need someone who has write or admin permissions in the repository to approve your pull request's changes in their review.
If a person with admin permissions chooses the Request changes option in a review, then that person must approve the pull request before it can be merged. If a reviewer who requests changes on a pull request isn't available, anyone with admin or write permission for the repository can dismiss the blocking review. For more information, see "Dismissing a pull request review."
Note: Repository admins can restrict the ability to dismiss pull request reviews to specific people or teams. For more information, see "Enabling required reviews for pull requests."
If you push a code-modifying commit to the branch of an approved pull request, the approval may be dismissed if repository admins have set up stale review dismissals. This doesn't apply if you push non-code-modifying commits, like merging the base branch into your pull request's branch.
Unless required reviews have been set up to include repository admins, people with admin permissions can merge a pull request regardless of reviews from other admins.
After all required reviewers have approved a pull request, you won't be able to merge it if there are other open pull requests with pending or rejected reviews and those pull requests have a head branch pointing to the same commit. Someone with write or admin permissions will need to approve or dismiss the blocking review on the other pull requests before you can merge.
You can't merge a pull request into a protected branch until someone with write or admin permissions approves it. If there are pending or rejected reviews, you'll receive an error message:
remote: error: GH006: Protected branch update failed for refs/heads/master. remote: error: Changes have been requested.