If you are using Office 365 and have implemented ADFS to manage the authentication to Office 365 services, this post is for you Smile

You may get the following error code – 8004789A – when logging on to Office 365 with web browser (Exchange Online OWA or SharePoint Online), while Outlook or any ActiveSync device is working fine


The solution is simple:

check if the Issuer (URI) URL is set to HTTPS; if the answer is yes, you have to change the configuration to use HTTP only

run the following command from a PowerShell window on the ADFS server

Add-PSSnapin Microsoft.Adfs.PowerShell
Set-ADFSProperties -Identifier "http://<your ADFS URL>/adfs/services/trust"
Restart-Service adfssrv

Also on the TMG side, check if the following settings are correctly set:

  • Apply link translation to this rule – available on the rule property below the Link Translation tab – is disabled


  • Verify normalization – available on the HTTP policy property – is disabled