Migration guide for Azure.Identity type consolidation into Azure.Core

Starting with Azure.Core 1.53.0, all public types that previously lived in the Azure.Identity package have been moved into Azure.Core. The Azure.Identity package (version 1.21.0 and later) is now a lightweight facade that forwards all types to Azure.Core using TypeForwardedTo attributes. This is a non-breaking change for most projects — existing code continues to compile and run transparently.

This guide covers the scenarios where you may need to take action.

Scenarios

Scenario	Build result	Remedy
Azure.Core only (no Azure.Identity reference)	✅ Builds	No action needed. Identity types are available directly through Azure.Core.
Azure.Core 1.53+ with Azure.Identity 1.21+	✅ Builds	No action needed. The facade forwards all types correctly.
Azure.Core 1.53+ with a direct Azure.Identity 1.19 or later reference	❌ CS0433	Remove the Azure.Identity PackageReference
Azure.Core 1.53+ with a transitive Azure.Identity 1.19 or later reference (via a third-party library)	❌ CS0433	Add a direct Azure.Identity 1.21+ PackageReference
Azure.Identity 1.21+ with Azure.Identity.Broker 1.5.0 or earlier	❌ TypeLoadException	Update Azure.Identity.Broker to 1.6.0+

Understanding CS0433

CS0433 is a compiler error that occurs when the same type is defined in two different assemblies. After the consolidation, types such as DefaultAzureCredential exist in both Azure.Core (where they now live) and in older versions of Azure.Identity (where they used to live). The compiler cannot determine which definition to use, so it reports the conflict.

Direct reference to an older Azure.Identity

If your project has a direct PackageReference to an Azure.Identity version older than 1.21.0 alongside Azure.Core 1.53.0 or later, you will see CS0433 errors.

Fix: Remove the Azure.Identity PackageReference from your project file. The types are now available through Azure.Core.

 <ItemGroup>
   <PackageReference Include="Azure.Core" Version="1.53.0" />
-  <PackageReference Include="Azure.Identity" Version="1.20.0" />
 </ItemGroup>

Transitive reference to an older Azure.Identity

If a third-party library that your project depends on brings in an older version of Azure.Identity transitively, you will see the same CS0433 errors even though your project does not directly reference Azure.Identity.

Fix: Add a direct PackageReference to Azure.Identity 1.21.0 or later. NuGet's nearest-wins rule ensures your direct reference takes precedence over the transitive one.

 <ItemGroup>
   <PackageReference Include="Azure.Core" Version="1.53.0" />
+  <PackageReference Include="Azure.Identity" Version="1.21.0" />
 </ItemGroup>

Frequently asked questions

Do I need to change any using directives?

No. All types remain in the Azure.Identity namespace. Only the assembly they are compiled into has changed.

Do I need to change any code?

No. The public API surface is identical. All classes, methods, properties, and constructors have the same signatures.

Will my existing NuGet packages still work at runtime?

Yes. The TypeForwardedTo attributes in the Azure.Identity 1.21.0 facade ensure that types serialized or referenced by the old assembly name resolve correctly at runtime.

I only depend on Azure.Core. Can I use DefaultAzureCredential without adding Azure.Identity?

Yes. Starting with Azure.Core 1.53.0, all credential types including DefaultAzureCredential are available without an Azure.Identity reference.

Is Azure.Identity obsolete?

No. The Azure.Identity package is not obsolete and will continue to exist indefinitely as a type-forwarding library. Projects that depend on Azure.Identity will continue to work without any changes.

Azure.Identity.Broker compatibility

If your project uses Azure.Identity.Broker for brokered authentication (WAM), you must update to Azure.Identity.Broker 1.6.0 or later when using Azure.Identity 1.21.0+ or Azure.Core 1.53.0+.

Older versions of Azure.Identity.Broker (1.5.0 and earlier) reference internal types that previously lived in the Azure.Identity assembly. After the type consolidation, those internal types moved to Azure.Core, and older Broker packages cannot resolve them at runtime.

Symptoms

When attempting brokered authentication, you will see an error such as:

TypeLoadException: Could not load type 'Azure.Identity.IMsalSettablePublicClientInitializerOptions'
from assembly 'Azure.Identity, Version=1.21.0.0, Culture=neutral, PublicKeyToken=92742159e12e44c8'.

This may surface as a connection failure when using libraries like Microsoft.Data.SqlClient with Authentication=ActiveDirectoryDefault.

Fix

Update Azure.Identity.Broker to 1.6.0 or later:

 <ItemGroup>
-  <PackageReference Include="Azure.Identity.Broker" Version="1.5.0" />
+  <PackageReference Include="Azure.Identity.Broker" Version="1.6.0" />
 </ItemGroup>