Microsoft Azure

What happened?Between 21:45 UTC and 23:23 UTC on 15 June 2026, Azure customers leveraging services which depend upon Microsoft Artifact Registry (MAR) may have experienced 401 authentication errors when attempting to pull images from MAR .  This incident is now mitigated. Further details will be provided directly to impacted customers through the Azure Portal.

Impact Statement: Starting at 21:45 UTC on 15 June 2026, a subset of Azure customers leveraging services which depend upon MCR (Microsoft Container Registry) for storing images may experience 401 authentication errors for requests attempting to pull Microsoft images from mcr.microsoft.com.Current Status: We detected this issue via internal service monitoring upon identifying a spike of 401 errors. We’ve identified a potential underlying factor to be a recent update which introduced a code regression, and we've completed roll out of a hotfix to address the code regression and mitigate impact for affected customers. We are closely monitoring internal telemetry to validate full mitigation and prevent further occurrences. The next update will be provided within 60 minutes, or as events warrant.

We are actively investigating customer alerts of 401 authentication errors when pulling images from mcr.microsoft.com. We’ve identified a potential underlying factor related to a recent update made to a backed service and we are actively working on determining mitigation workstreams. More information will be provided shortly.