Taking back Scrum - Defects Over Stories
Individuals and Interactions over Processes and Tools.
That applies to Scrum because Scrum is a tool. When a developer finds a defect in the sprint, the defect work takes precedence over any stories in the sprint. As a product owner, it's important to know this. If the product owner doesn't know it, then it's up to the scrum master to correct them.
Per the scrum guide:
During the Sprint: - No changes are made that would endanger the Sprint Goal
Nope. A defect should take precedence, and it is the Product Owner's job to recognize this and adjust the plan accordingly.
That's right folks - we break this rule because of #1. We are software developers building quality software and if an individual is blocked because of a defect, we fix the defect before worrying about whether the sprint goal is achieved.