About required reviews for pull requests
Required reviews ensure that pull requests have a specific number of approving reviews before collaborators can make changes to a protected branch.
Protected branches are available in public repositories with GitHub Free, and in public and private repositories with GitHub Pro, GitHub Team, GitHub Enterprise Cloud, and GitHub Enterprise Server.
If you've enforced branch protections in your repository, you can set up required reviews. For more information about enforcing branch protections, see "Configuring protected branches." For more information about setting up required reviews, see "Enabling required reviews for pull requests."
Repository administrators can require that all pull requests receive a specific number of approving reviews from people with write or admin permissions in the repository or from a designated code owner before they're merged into a protected 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, you won't be able to merge your pull request until the required number of reviewers with write or admin permissions in the repository approve your pull request's changes in their review. For more information about repository permission levels, see "Repository permission levels for an organization." If review is required from a designated code owner and the pull request affects code that has a designated owner, approval from that owner is required.
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.