Copilot Code Review is degraded, and not returning responses to users
This summary is created by Generative AI and may differ from the actual content.
Overview
Copilot Code Review experienced a service degradation between 15:15 UTC and 18:22 UTC on December 15, 2025, resulting in 46.97% of pull request review requests failing with the error message 'Copilot encountered an error and was unable to review this pull request. You can try again by re-requesting a review.', and was resolved by temporarily bypassing fix suggestions, increasing worker capacity, and rolling out a model configuration change, with follow-up actions including increasing baseline worker capacity, adding instrumentation, and improving load-shedding and alerting, and an ongoing investigation into long-term availability and scaling strategies.
Impact
46.97% of pull request review requests failed, requiring users to re-request a review
Trigger
Elevated response times in an internal, model-backed dependency
Detection
Impacted users saw the error message and reported the issue, which was then investigated
Resolution
Temporarily bypassing fix suggestions, increasing worker capacity, and rolling out a model configuration change
Root Cause
Elevated response times in an internal, model-backed dependency, leading to request timeouts and backpressure in the review processing pipeline