Microsoft 365 Alert : Service Degradation – SharePoint Online – Users can’t access SharePoint Online sites via Microsoft Edge – RESOLVED

01/09/2022 17:10:00 PM (BST)

NHSMail Reference : INC31402956

Microsoft Reference : SP424193

Issue Status : RESOLVED

Issue Description : Users can’t access SharePoint Online sites via Microsoft Edge.

More Info : Users can access SharePoint Online sites from other browsers and users can temporarily restore access to sites through Microsoft Edge by clearing their cache.

Users see the following error message when they encounter this issue:
“AADSTS900411: The request is not properly formatted. The parameter ‘login_hint’ is duplicated”

Scope of impact : Impact may occur for any user attempting to access SharePoint Online sites via Microsoft Edge build 102-104.0.1293.70.

Final Update : 22/09/2022 15:28:00 PM – Microsoft received confirmation from affected users that the fix has restored the affected URL property to functionality and impact is remediated.

Root cause : A Microsoft Edge browser client feature that streamlines Azure AD SSO for users with multiple Azure AD accounts on one machine utilizes the URL property “login_hint” to disambiguate between accounts during the authentication process. An interaction occurred between SharePoint Online sites and the Edge client browsers running on builds 102-104 where the property is escaped to “login5%hint” and the Edge clients don’t correctly identify this as the required property, inserting a duplicate, non-escaped version when authenticating to these sites.

Next steps : Microsoft are reviewing the SharePoint Online codebase as it pertains to Microsoft Edge interactions to reinforce the SharePoint Online service environment against similar impact in the future.

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