What causes 'bad days' for developers?

A Microsoft study found engineering system friction to be the main cause of "bad days" for software developers, with unreliable tools and slow processes leading to reduced productivity and increased stress. Senior engineers reported frustration, while junior engineers experienced more self-doubt. The study combined developer feedback with telemetry data, confirming that bad days resulted in lower work quality and quantity. Some senior developers even considered job changes. This research emphasizes the need to address systemic issues to enhance developer satisfaction and productivity.