Microsoft Office 365 users receive the error code 80090016 when signing in from an Office application like Word or Excel to the Office 365 account:

Cause

It is no longer possible to log in to the Microsoft Office 365 account from an Office 2019 or Microsoft 365 application. The password entry no longer appears, or no response follows after the entry. The credentials underlying the Microsoft Trusted Platform are no longer valid.

Solution

The Trusted Platform credentials can be reset. Under the user profile path %localappdata\%Packages it is the folder Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy.

By typing into the Explorer address bar: %localappdata%\Packages the folder Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy Rename to _old.

C:\Users\<username>\appdata\local\Packages\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy_old

The next time you log on to your Microsoft Office 365 account, it will become the Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy folder recreated. The newly generated credentials can be processed correctly by the Trusted Platform.