Modern authentication failed, Your status code is 4c7 – Microsoft Teams error

Microsoft teams is a unified communications and collaboration platform that combines permanent workplace chat, video meetings, file storage and application integration. If when you try to connect to Microsoft Teams when you connect from a corporate network in which Active Directory Federation Services (AD FS) is installed and you experience the problem “Modern authentication failed “ error message, then this message might interest you. In this article, we will identify the potential cause and also provide the possible solution that you can try to resolve this problem.

Modern authentication failed, 4c7 status code – Microsoft Teams

When authentication fails, you will receive the error message as described below:

Modern authentication failed here, but you can still log in. Your status code is 4c7.

And if you check the logs, you can see information similar to the following:

DateTime< 7124> – info – SSO: SSO requires identification information. Status: caa10001. Windows authentication attempt.
DateTime< 7124> – info – SSO requires credentials. Status: caa10001. Windows authentication attempt. diag: 1
DateTime<7124> – info – SSO: (not joined to the domain) No user present. Status: 3399548929
DateTime<7124> – error – SSO: ssoerr – (state) Unable to get errCode. Err: Error: ADAL error: 0xCAA10001SSO: ssoerr – (status) Unable to get errorDesc. Err: Error: ADAL error: 0xCAA10001

To resolve the Modern authentication failed – 4v7 status code error message, you will need to enable form authentication using the AD FS Microsoft Management Console (MMC) snap-in on the computer that has the local copy of Active Directory. To do so, follow these steps:

1. In the navigation pane, go to Authentication policies.
2. Below Actions in the details pane, select Change global primary authentication.
3. On the Intranet tab, select Form authentication.
4. To select Okay (or Apply).

According to Microsoft, this error occurs because Microsoft Teams requires form authentication. When you deploy AD FS, form authentication is not enabled by default for the intranet.

Form-based authentication is a technical term in the context of web-based online computer systems and the Internet. In general, it refers to the notion of a user being presented with an editable “form” to fill out and submit in order to connect to a system or service.

The advantage of form authentication is that users do not need to be members of a domain-based network to access your application. Thus, the number of web applications uses the form of authentication in their web application.

There are three types of authentication in ASP.NET:

1. Windows authentication
2. Form authentication
3. Passport authentication

If Integrated Windows authentication fails, you are prompted to log in using form authentication.