I have a website where people can upload documents, and view them later at their convenience. I store the binary info along with the mime type in my db, and later just stream the binary content straight to the browser.
This works for for every file type except Office 2007 files. When I try to view the Office 2007 files, I get a popup requesting credentials. After I dismiss the the dialog (by canceling), I get another popup like the one below:
After also dismissing this dialog (by clicking ‘Yes’), the document finally opens. What gives? Does the browser really not know how to handle Office 2007 files? I checked the mime-type I’m saving, and everything looks correct. Any ideas on what I can do to get rid of these dialogs when trying to open a file?
Check out this explanation on VS Office Developer.
It gives a registry hack which your users could choose to apply to rid suppress this warning.