If you unable to connect Office Desktop applications to the Office 365 account, apply one of the following methods: Method 1. How to FIX: Cannot Sign-in to Office 365 in Office Desktop Apps.
Outlook needs password, but dialog box disappears.This tutorial contains instructions to fix the following Sign-in problems in Office desktop applications, when using an Office 365 or Office 365 Business account:
However, after typing the user's credentials, the authentication fails every time, despite the fact that the user can log on without any problems in Office 365 and Outlook on the web. The following issue, was appear in Outlook after updating the Office 365 applications on a Windows 10 PC: After launching Outlook, the program prompts to authenticate with the Office 365 account.
