• Sharepoint 2016 Farm (running FP1)
  • Office Online Server

We have 1 web applications, with 2 zones (default and internet)

The default zone has windows auth, while the extended internet zone has Forms Based auth configured.

The AAMs are configured as:

We also have our OOS server at https://oos.example.com

Viewing documents in either zone works fine, and editing documents in browser works from the default zone, but not from the internet zone.

When click "Edit in browser" in the internet zone (logged in with FBA), we get the error: PowerPoint Online cannot open this presentation for editing. Please try again later.

Looking at the Event logs on the OOS server yeilds this error:

 Could not contact WOPI End Point. Error details - 'FileNotFound url - https://intranet.example.com/_vti_bin/wopi.ashx/files/...

Looking through the ULS logs show similar errors but too verbose to show here.

Why is it trying to use the default AAM instead of the one being accessed, when it uses that for the view-only mode? How do I allow FBA users to edit in browser?

1 Answer 1


So I Opened a ticket with Microsoft and they said that this is "intended behavior" and that Office Online Server will not work for the extended web app in this configuration.

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