Modern authentication failed here, but you'll still be able to sign in.
Your status code is 4c7
If you receive the above message with code 4c7 in Teams application when trying to login via your companies AD FS (active directory) the most common reason could be that when AD FS was deployed the Forms Authentication was not enabled. This option is not enabled by default.
Fix:In order to fix this issue, the Forms Authentication option needs to be enabled using the AD FS MMC (Microsoft Management Console) snap-in on the computer that has the local copy of AD,
Steps to enable Forms Authentication:- Under Navigation Pane look for Authentication Policies,
- Under Details Pane -> Actions -> Select Edit Global Primary Authentication,
- Under Intranet tab select Forms Authentication.
- Click on OK to apply changes.

Have Questions? Post them here!
More Posts related to Teams,
- Enable and reduce background noise in Microsoft Teams with AI-based noise suppression
- Fix: Teams is in preview in Safari on Mac
- Microsoft Teams - Where would you like to start - Business or Personal
- How to Install Microsoft Teams App on M1 Mac
- [Fix] Modern authentication failed here, but youll still be able to sign in. Your status code is 4c7 - Microsoft Teams
- Microsoft Teams Error code - 6 issue
- How to track and download Microsoft Teams meeting attendance report of participants/students
- How to Change name on Microsoft Teams Application
- Cannot create new Microsoft Team using PowerShell, even as Admin
- Fix Microsoft Teams error We're sorryβwe've run into an issue Try again
- Fix Microsoft Teams Admin Center error - The Security zone setting isn't configured correctly
- How to enable Do Not Disturb (DND) mode in Microsoft Teams
- Users experience call quality issue, voice distortion, disconnection with Microsoft Teams call and meeting
- Microsoft Teams meeting Full Screen mode option missing - bring it back
- How to enable Do Not Disturb (DND) mode in Microsoft Teams
- How to Enable Dark Mode Theme in Microsoft Teams
- How to enable, create and use Virtual Breakout Rooms in Microsoft Teams
- Teams - You're offline. Messages you send while offline will be sent when you're back online
- Cannot open or preview pdf with view only and restricted download access in Microsoft Teams
- How to uninstall/remove or disable Microsoft Teams
- [Microsoft Teams] You're not on Teams yet, but you can set it up for your organization.
- How to turn on channel notifications for Microsoft Teams
- Microsoft Teams enable or disable Spell check
- Microsoft Teams adds New Conversation Button
- How to start Microsoft Teams on Mac Startup
More Posts:
- How to create a SharePoint list from an existing list with same columns, views, formatting, data - SharePoint
- Sign in as different user missing in SharePoint 2013, how to enable - SharePoint
- SharePoint An unexpected error has occurred - Correlation ID and PowerShell Merge-SPlogfile - SharePoint
- How to change SharePoint Online site collection or subsite URL address - SharePoint
- Failed to load resource: net::ERR_CACHE_MISS PHP - PHP
- How to install Java 11 on Mac - Java
- Calculate Volume of Sphere - C-Program
- How to check installed Tomcat version - Tomcat