Unable to open particular URLs from inside Word

Thanks.  

The URLs in Word and the 404 message are identical.

I think I figured it out:  The URL is to a private repository on GitHub.

Links to public GitHub repositories work just fine in Word.  But I get the 404 if it's a private repository.  And this happens even though I'm signed in to Github.  Like I said, if I copy the link to a browser, it works.  That's because the browser understands that I'm signed in.

The question is:  Why doesn't Word know that I'm signed in?

Btw, the same problem happens in Excel.  The problem does not happen in Outlook.

I  agree, it sounds like a bug. Unfortunately, since Word was developed long before the Internet, its hyperlinks are not 100% compliant with web standards.

Does the URL in the 404 message differ from the one in the Word document, by even one character?

Because the message says that the "Internet site reports that the item you requested could not be found", the part of the URL that specifies the domain (somesite.com or whatever the address is) is correct. If the incorrect character(s) were in that part, you would get a different message.

That implies that the objectionable part is either the page address (somepage.htm or something like that) or a parameter after the page (either an anchor subaddress following a # sign, or a database parameter following a question mark).

Thanks, but there is no number sign (#).

If the URLs that don't work include a hash (#), look at this thread: http://stackoverflow.com/questions/25070176/hyperlink-changes-from-to-20-20-when-clicked-in-excel