Azure AD B2C: Clients must send a client_secret when redeeming a confidential grant

Question

I try to setup authentification for an Angular app using authorization code and Azure AD B2C (oidc-client on client side), but I\'m getting these errors from Angular:

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Answer 1

I suspect that your code is fine but ...

The last I heard, Azure AD does not allow cross origin calls to the token endpoint - and therefore does not support the Authorization Code Flow (PKCE) that SPAs should use in 2019.

Unless I'm mistaken this will mean you need to use the (unrecommended) implicit flow when integrating with Azure AD. There have been problems for SPAs for a couple of years now.

Out of interest I wrote a couple of posts on Azure SPA workrounds a couple of years ag - I suspect some of this is still relevant: https://authguidance.com/2017/11/30/azure-active-directory-setup/

Answer 2

Your image shows a CORS error.

I'm not sure if oidc-client works OOTB with B2C. It's more for identityserver.

Have a look at the msal.js sample.

Answer 3

I had the exact same issue as you and was just able to resolve it.

AD is requesting the client_secret from you, because it isn't configured for PKCE yet. To tell AD that you want to use PKCE for a specific redirect url you need to set its type from 'Web' to 'Spa'. This can be done in the manifest.

Search for the property replyUrlsWithType in the Manifest and look for your .../signin-callback url. Change its type to 'Spa' and you should be good.

eg.:

"replyUrlsWithType": [
    {
        "url": "http://localhost:8080/signin-callback",
        "type": "Spa"
    },
]

The configured url will now disappear from your Authorization page but thats ok -> it's still present in the Manifest. The MS team is working on this new type.

Also make sure you marked your application as a public client.

For more information, see my answer here: Is Active Directory not supporting Authorization Code Flow with PKCE?