A supplier responsible for an important project component cannot deliver due to a large-scale labor problem. Which document should the project manager update and use to inform relevant stakeholders?

The issue log is the correct document to update because a labor problem that has already occurred and is impacting a project component is an active issue, not a potential risk. The issue log tracks and manages all project issues, including their description, impact, owner, and resolution plan. The project manager uses it to communicate the status of issues to stakeholders and ensure timely resolution. The project schedule would be updated after the impact of the issue on timelines is assessed, but it's not the primary document for tracking the problem itself. The risk register is for potential future events, whereas this labor problem has already happened. A change request might be initiated as a result of the issue (e.g., to find a new supplier or adjust scope), but the issue log is where the problem is first formally recorded and managed.