Microsoft Is Rotating Its NuGet Author-Signing Certificate: Fix trustedSigners Before NU3034 Hits
Starting September 23, 2026, Microsoft packages on NuGet get author-signed with a new certificate (SHA-256 9A1B131B...). If your nuget.config pins Microsoft in trustedSigners, restores will fail with NU3034. Here is the fix, including the correct dotnet nuget trust command.