Impact Statement: Starting at 06:45 UTC on 26 Jun 2023 you have been identified as a customer using Azure Front Door who may have encountered intermittent HTTP 502 errors response codes when accessing Azure Front Door CDN services.

Current Status: Based on our initial investigation, we have determined that a subset of AFD POPs became unhealthy and unable to handle the load of incoming requests, which in turn impacted Azure Front Door availability.

After a successfully simulation we are currently applying the potential mitigation workstream, by removing impacted instances from rotation while monitoring traffic allocations to remaining healthy cluster. The first set of impacted instances have been successfully removed at 15:30 UTC on 26 Jun 2023. Since the removal we have been seeing a reduction of errors and we will continue to monitor impact. We are currently working on removing the rest of the impacted instances and allocating the resources to a healthy alternative. Some customers may already begin to see signs of recovery. The next update will be provided in 60 minutes, or as events warrant.

Summary of Impact: Between 06:45 UTC and 17:15 UTC on 26 Jun 2023 you were identified as a customer using Azure Front Door who may have encountered intermittent HTTP 502 errors response codes when accessing Azure Front Door CDN services.

This issue is now mitigated, more information on mitigation will be provided shortly.

Summary of Impact: Between 06:45 UTC and 17:15 UTC on 26 Jun 2023 you were identified as a customer using Azure Front Door who may have encountered intermittent HTTP 502 errors response codes when accessing Azure Front Door CDN services.

Preliminary Root Cause: We found that a subset of AFD POPs were throwing errors and unable to process requests. 

Mitigation: We moved the resources from the affected AFD POPs to healthy alternatives which returned the service to a healthy state.

Next Steps: We will continue to investigate to establish the full root cause and prevent future occurrences. Stay informed about Azure service issues by creating custom service health alerts: https://aka.ms/ash-videos for video tutorials and https://aka.ms/ash-alerts for how-to documentation. 

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