Does this occur in other browsers? Are you able to share with us the website where this is occurring?

You can inspect the MIME database key with the registry editor (regedit.exe) and do a search for that MIME type (file extension) via Ctrl+F. Be cautious with editing the registry as there is NO UNDO possible: all changes are applied immediately. You can export key(s) in the registry editor before making changes. You can check specific file extension keys (e.g. .jpg) in the registry with the registry editor.

• HKEY_CLASSES_ROOT\.xxx

You can check a possibly linked MIME type in the MIME Database registry key.

• HKEY_CLASSES_ROOT\MIME\Database\Content Type\

Hi Paula, just to confirm, the actual downloaded file opens normally in Visio if you fix the file extension from .htm back to .vsdx? So the problem is the extra file extension, and not that the download itself is corrupted.

Do you know whether the download is coming from a static file on a server, or is being generated dynamically by a script in the page?

Andrew- The website I am downloading the Visio file from is First to File (prod.firsttofile.com). I have not checked other browsers, because I legit use Firefox for everything else... foxes have me hooked.

cor-el: This is on a work laptop, so I cannot, sadly, edit the registry. I tried running repairs on the system as administrator, but no dice. I did search the registry for .vsdx and .htm, but nothing looked at of the ordinary. For example, .vsdx wasn’t in a folder under Firefox document. It was also a long day/night and maybe I overlooked something. But the one edit I tried to do, it wouldn’t let me.

I can edit the handler file for Firefox in my profile folder though.

Jscher2000- I can remove the .htm extension, and the Visio file opens perfectly fine and normal. However, I rename files a lot and do not like to leave “view file extensions” checked. I do use Visio somewhat often, but most of the time my coworker remembers to save properly.

After a quick search, I believe First-to-File (FTF) is a dynamic site. The Visio file is created by someone else, and they upload it to FTF. In order for me to be able to open the file, I must click on the file and save (I cannot just open Visio files) to my computer, then open the Visio file. Firefox has no problem recognizing .vsd files as Microsoft Visio Drawings, but it does not like .vsdx.

I had this issue before, but there are no notes for IT on how they fixed it, and it was RIGHT before we went on quarantine. I am super good at giving IT new head scratchers. =)