Urgent Deadline: Update Legacy .NET Domains Before January 7, 2025, to Prevent Service Disruptions

Microsoft's Critical Update for .NET Domains

Microsoft has announced an unexpected change in how .NET installers and archives are distributed, urging developers to update their production and DevOps infrastructure before January 7, 2025.

According to Richard Lander, a program manager on the .NET team, while most users may remain unaffected, it is crucial to validate potential impact and prepare for possible downtime or disruptions.

Why Is This Change Happening?

Several .NET binaries and installers are currently hosted on Azure Content Delivery Network (CDN) domains, specifically:

• dotnetcli.azureedge.net

• dotnetbuilds.azureedge.net

These domains are hosted on Edgio, a platform that recently became part of Akamai following its bankruptcy. Due to this transition, the Edgio platform will cease operations on January 15, 2025.

To ensure continuity, Microsoft is migrating to Azure Front Door CDNs and has stated that customer workloads will automatically transition by January 7, 2025, unless action is taken.

Action Required: Key Steps for Developers

1. Check for Dependencies
   Developers must review their codebases and verify if they rely on .azureedge.net domains.

2. Prepare for Migration
   If automatic migration isn’t feasible, users should plan to transition manually before January 14, 2025.

3. Feature Flag for CDN Selection

   • If migrating to Akamai or another CDN provider, set the feature flag:
     DoNotForceMigrateEdgioCDNProfiles

   • This prevents automatic migration to Azure Front Door.

4. Configuration Freeze from January 3, 2025

   • Microsoft has announced a freeze on Azure CDN by Edgio configurations starting January 3, 2025.

   • While services will remain operational, no updates to CDN profiles will be possible.

Risks and Recommendations

Microsoft advises against continued reliance on *.azureedge.net and *.azurefd.net domains due to potential availability risks. Instead, users should migrate to custom domains to avoid disruptions.

To address security concerns, Microsoft has taken control of the azureedge.net domain to prevent potential malware distribution or supply chain attacks. However, Microsoft has clarified that the old domain names cannot resolve to the new servers.

Required Updates to .NET Domains

Developers must update references in their projects:

• Replace: dotnetcli.azureedge.net
  With: builds.dotnet.microsoft.com

• Replace: dotnetcli.blob.core.windows.net
  With: builds.dotnet.microsoft.com

Final Reminder

Ensure your systems are updated before January 7, 2025, to prevent any service interruptions. Delays in migration could lead to unplanned downtime and potential security vulnerabilities.

For further details, visit Microsoft's official documentation on .NET migration updates.