Office 365/2019/2016 Error: Another Account from Your Organization Is Already Signed in on Computer

In some cases, when you sign in to an Office 365 (Microsoft 365) or Office 2019/2016/2013 application on Windows with a Microsoft account (or an Azure account), the following error may appear:

Sorry, another account from your organization is already signed in on this computer.

The issue occurs if a user from the same organization (tenant) your Microsoft 365 account belongs to is signed in on this computer or to an Office app (Word, Excel, Outlook, etc.). The matter is that Microsoft 365 supports only one session for users of the same organization.

The best solution is to sign out the previous user from all Office 365 (Microsoft 365) apps. To do it:

1. You can finish a previous user session by signing them out of an Office app or Windows (using the Sign Out button on the top right of your Office app or in the menu: File -> Account);
2. Remove all connected Office services from your profile (File -> Account -> Connected Services -> Remove Services);
3. Do it for all Microsoft Office apps (Excel, PowerPoint, Outlook, Word, etc.);
4. Restart your computer;
5. Open an Office app and sign in with your Microsoft account.

If this simple method to clear the previous account data from your computer has not helped, you have to completely remove this Microsoft 365 profile and saved usernames and passwords from Windows Credential Manager.

1. Start Windows Credential Manager using the command: control /name Microsoft.CredentialManager (or go to Control Panel\User Accounts\Credential Manager);
2. Remove saved Office and Microsoft accounts under the Generic Credentials section;
3. Open the Registry Editor (regedit.exe) and go to HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Identity\Identities (for Office 365/2019 and 2016);
   If you have Office 2013, go to another registry key: HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Common\Identity\Identities
4. Use the values of EmailAddress, FirstName, and LastName parameters to search for registry keys that store information about other users of your organization. Remove the registry keys that you have found under the Identities section (they contain profile data);
5. Clear Office license activation data: %localappdata%\Microsoft\Office\16.0\Licensing\
6. Restart your computer and sign in to an Office app using your Microsoft 365 account.

If it has not helped or you see a blank Office/Teams/Word sign-in window, make sure your copy of Office is allowed to use Modern Authentication. This requires a registry setting to be set (for Office 2013 and 2016):

HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Common\Identity
DWORD:EnableADAL
Value: 1

If the problem occurs on an RDS server with Office 365 ProPlus (Microsoft 365 App for Enterprise), make sure that your Office is installed with the SharedComputerLicensing option enabled.