[Bug] Script error “Object doesn’t support property or method ‘isInteger’” appears when trying to sign in.

Description We are using the Microsoft.Identity.Client nuget package for user authentication in our WPF desktop client. The actual problem is that the script error “Object doesn’t support property or method ‘isInteger’” appears during sign-in.

Which version of MSAL.NET are you using? Tried both versions 4.36.1 and 4.46.0.

Platform .NET Framework 4.6.1

Steps to reproduce

1. Open “Sign in to your account” window and enter your password.

2. Click “Sign in” button (user is navigated to the “Help us protect your account” page).

3. Click “Next” button on “Help us protect your account” page.

Expected behavior The user should be asked to install Microsoft Authenticator and be able to setup MFA.

Actual behavior The script error “Object doesn’t support property or method ‘isInteger’” appears (see the screenshot below). The error is thrown in main.486a7dba.js.

Is this a new or existing app? The app is in production, I haven’t upgraded MSAL (current version 4.36.1), but started seeing this issue.

Repro

IPublicClientApplication publicClientApplication = PublicClientApplicationBuilder
	.Create(someClientId)
	.WithRedirectUri("msal{ClientId}://auth")
	.Build(); 
	
AcquireTokenInteractiveParameterBuilder builder = publicClientApplication
	.AcquireTokenInteractive(new string[] { "user.read" })
	.WithPrompt(Prompt.ForceLogin)
	.WithLoginHint(someEmail);

AuthenticationResult authenticationResult = await builder.ExecuteAsync();

[bgavrilMS]

The solution here is to use WAM: https://aka.ms/msal-net-wam for AAD accounts. For B2C accounts, Microsoft.Identity.Client.Desktop has WebView2 support.

[bgavrilMS]

Cl,osing as external.