GitHub Merge Queue Compatibility with CircleCI

Overview

If you're using GitHub's merge queue feature together with CircleCI's "Prevent unregistered users from triggering builds" setting, you may experience failed or blocked builds. This article explains why this happens and how to resolve the issue.

What's Happening

As of June 2023, GitHub changed the behavior of their merge queue to attribute merges to the GitHub Merge Queue bot (github-merge-queue[bot]) instead of the user who initiated the merge.

When this bot triggers a build in CircleCI, the system recognizes it as an unregistered user. If you have the "Prevent unregistered users from triggering builds" setting enabled in your CircleCI plan settings, these builds will be blocked.

How to Identify the Issue

You may be experiencing this issue if:

1. You're using GitHub's merge queue feature
2. You have CircleCI's "Prevent unregistered users from triggering builds" setting enabled
3. Builds on your default branch (e.g., master or main) are failing after being merged via the queue
4. The error message indicates that the build was blocked because of an unregistered user

Solution

Temporary Workaround

To immediately resolve the issue, you can disable the "Prevent unregistered users from triggering builds" setting:

1. Navigate to your organization settings in CircleCI
2. Go to Plan > Usage Controls
3. Find the "Prevent unregistered users from triggering builds" option
4. Turn it off

Note: This is a security/cost control measure. Disabling it will allow any user (including unregistered bots) to trigger workflows in your CircleCI setup.

Additional Information

• This setting only affects builds triggered via webhooks from your VCS (like GitHub)
• Scheduled workflows and manually triggered workflows are not affected by this setting

Additional Resources: 

• CircleCI Documentation: Prevent unregistered users from spending credits
• What is an "Unregistered User"?