According to the PMBOK Guide, 7th edition, a root cause analysis is a technique used to identify the underlying factors or causes of a problem or issue. It helps to prevent recurrence of the same or similar problems in the future. A quality breach is a deviation from the quality standards or requirements agreed upon with the customer. It can result in customer dissatisfaction, rework, delays, or defects. Therefore, the project manager should run a root cause analysis to find out why the product has discrepancies with the customer's request and take corrective actions to prevent further quality issues. The project manager should also update the quality management plan to reflect any changes in the quality processes, tools, metrics, or responsibilities.
This will help to ensure that the project delivers a product that meets the customer's expectations and requirements. References:
* PMBOK Guide, 7th edition, page 237, section 8.2.3.1, Root Cause Analysis
* PMBOK Guide, 7th edition, page 238, section 8.2.3.2, Quality Management Plan Updates