File upload/download problems using Internet Explorer to a Sharepoint site

Question

A cheeseburger to the first person who can help me make sense of this. I have a page in a Sharepoint app that uses Telerik's RadUpload to upload files. This has worked for months; last week it stopped working (in Internet Explorer, this detail is important). After talking with a co-worker about the problem, I tried the upload with Firefox; it worked. Not only that, all subsequent uploads from Internet Explorer started working. Flash forward an hour, and the aforementioned coworker, on another Sharepoint site, running on different servers, was having problems downloading (using Internet Explorer). Being half serious, half smart-aleck, I said 'try it in Firefox'. Not only did that work, ALL SUBSEQUENT DOWNLOADS IN INTERNET EXPLORER WORKED! And he re-produced this behavior on another machine. My fear is that this a browser issue. All advice will be greatly appreciated.

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Answer 1

Was it as simple as IE not re-downloading miss-cached .js file, maybe, that firefox did download, making IE work after that?

Pretty gnarly to debug.

Answer 2

IE will try and present credentials to a server it knows to be in its Local Intranet zone when it tries to connect (depending on the setting of "Automatic logon only in Intranet zone").

Firefox will only present credentials when prompted, and will generally ask you by popping up a box (unless you've configured a list of sites for it to always present NTLM credentials to).

I've seen a similar case with Sharepoint where you can cause IE to work by logging in with Firefox. I theorized it was due to a permission on a remote resource being for "Authenticated Users", and you're causing your user to authenticate by logging in forcefully. We eventually set the "Automatic logon only in Intranet zone" to "Prompt" and it worked. My theory there was that it wasn't detecting the site as being in the Local Intranet zone for some reason. If you're not accessing a domain with no .'s in it, try also setting your Local Intranet site policy to match the full domain of the Sharepoint server, not just *.example.com - I've read that that can help.