Migrating Adal To Msal

ADAL to MSAL Migration

Overview

Migrate Azure AD authentication from ADAL (Active Directory Authentication Library) to MSAL (Microsoft Authentication Library). ADAL reached end of support in June 2023, and MSAL is the recommended replacement for all Azure AD / Microsoft Entra ID authentication scenarios. The core change is replacing AuthenticationContext with MSAL's fluent application builders and converting resource-based token requests to scope-based requests.

Related skills: For OWIN-based cookie or OAuth authentication migration, see migrating-owin-cookie-auth and migrating-owin-oauth-to-jwt.

Package Reference Changes

Old Reference (Remove)

<PackageReference Include="Microsoft.IdentityModel.Clients.ActiveDirectory" Version="5.x.x" />

New Reference (Add)

<PackageReference Include="Microsoft.Identity.Client" Version="{latest-stable}" />

Use tools or NuGet to find the latest stable version.

Workflow

Migration Progress:
- [ ] Step 1: Detect ADAL usage patterns
- [ ] Step 2: Update package references
- [ ] Step 3: Replace AuthenticationContext with application builders
- [ ] Step 4: Convert resource strings to scopes
- [ ] Step 5: Update token cache serialization
- [ ] Step 6: Migrate credential flows
- [ ] Step 7: Build and verify

Step 1: Detect ADAL Usage Patterns

Scan the project for:

• using Microsoft.IdentityModel.Clients.ActiveDirectory; statements
• AuthenticationContext instantiation
• AcquireTokenAsync calls with resource parameters
• UserCredential or UserPasswordCredential usage
• ClientCredential or ClientAssertionCertificate usage
• Custom TokenCache implementations

If the project already uses Microsoft.Identity.Client, no migration is needed.

Step 2: Update Package References

Remove the ADAL package and add MSAL (see "Package Reference Changes" above). Update the using directive:

// Old
using Microsoft.IdentityModel.Clients.ActiveDirectory;

// New
using Microsoft.Identity.Client;

Step 3: Replace AuthenticationContext with Application Builders

MSAL distinguishes between public client apps (desktop/mobile) and confidential client apps (web/daemon). Choose the appropriate builder based on the application type.

Step 4: Convert Resource Strings to Scopes

ADAL uses a single resource string; MSAL uses a scopes array. For v1-to-v2 parity, append /.default to the resource URI:

// ADAL
var result = await context.AcquireTokenAsync("https://graph.microsoft.com", credential);

// MSAL
var result = await app.AcquireTokenForClient(new[] { "https://graph.microsoft.com/.default" }).ExecuteAsync();

The /.default scope requests all statically configured permissions, matching ADAL's resource-based behavior.

Step 5: Update Token Cache Serialization

ADAL's TokenCache and its BeforeAccess/AfterAccess events are replaced by MSAL's token cache serialization API. MSAL does not persist the cache by default — add serialization explicitly for web apps and daemon services:

// MSAL cache serialization (example using Microsoft.Identity.Web)
app.AddInMemoryTokenCache();
// or
app.AddDistributedTokenCache(services => { /* configure */ });

For desktop apps, MSAL provides built-in file-based cache helpers via Microsoft.Identity.Client.Extensions.Msal.

Step 6: Migrate Credential Flows

Note: AuthenticationResult.AccessToken works the same way in both libraries.

Step 7: Build and Verify

1. Build the project:

   dotnet build
   

2. Verify token acquisition succeeds against your Azure AD / Entra ID tenant
3. Confirm that AuthenticationResult.AccessToken is returned and API calls function correctly
4. Check that token caching works as expected (cache hit on second request)

Troubleshooting

"AADSTS50011: The reply URL does not match"

MSAL constructs redirect URIs differently than ADAL. For public client apps, use http://localhost or the platform-specific default. Update the app registration in the Azure portal to match.

Authority URL Changes

ADAL uses https://login.microsoftonline.com/{tenant} by default. MSAL supports the same format but also accepts https://login.microsoftonline.com/{tenant}/v2.0. Use the v2.0 endpoint for new integrations; omit it for strict v1 parity.

Token Cache Not Persisting

MSAL's default cache is in-memory only. For web apps, add Microsoft.Identity.Web and call AddInMemoryTokenCache() or AddDistributedTokenCache(). For desktop apps, add Microsoft.Identity.Client.Extensions.Msal and use MsalCacheHelper.

Multi-Tenant Apps

If the ADAL code used https://login.microsoftonline.com/common, set .WithAuthority(AadAuthorityAudience.AzureAdAndPersonalMicrosoftAccount) or .WithAuthority("https://login.microsoftonline.com/common") on the MSAL builder.