If you enable Modern Auth in Exchange Online with Set-OrganizationConfig -OAuth2ClientProfileEnabled $true , and then start seeing this error in Office 2016 or 2013 clients:
AADSTS165000: Invalid request: the request tokens do not match the user context. One or more of the user context values (cookies; form fields; headers) were incorrect or invalid, these values should not be copied between requests or user sessions; always maintain ALL of the supplied values across a complete single user flow. Failure reasons:[Token is invalid;]
You need to re-activate Office.