We have SharePoint 2013 (on-prem), and some Word documents in a library. I have the library Opening Documents setting configured to Open in the client application.
This works just fine in IE (11), Chrome (58), and Edge (25) - clicking the document in-browser opens Microsoft Word, and the file is opened directly from SharePoint prompting for checkout, etc. Saving the document goes right back to SharePoint. In Firefox (53) though, I am prompted to open or save the file, and clicking Open just downloads the file to a temp directory, and opens locally instead of from SharePoint.
When I poke around in Chrome Dev Tools, I can see that the requested URL when I click the doc in the library is ms-word:ofv|u|https://example.com/library/document.docx, but Firefox Dev Tools reports it is requesting just https://example.com/library/document.docx, without the ms-word:ofv|u| prefix.
If I copy the Chrome requested URL with prefix into Firefox and load that directly, Firefox properly opens the file directly from SharePoint.
So it seems like SharePoint is providing a different link on my documents to Firefox than it does to other browsers. I tried loading the page in Chrome, but with my Firefox user-agent [Mozilla/5.0 (Windows NT 10.0; WOW64; rv:53.0) Gecko/20100101 Firefox/53.0], and sure enough - Chrome then downloads the file locally instead of opening it directly from SharePoint like it is supposed to.
Is there something wrong with my SharePoint install that is causing it to treat the Firefox user-agent differently? Something else I'm doing wrong?
