Question: I have a pretty weird problem. I have an iMac and have just had my old HDD replaced with an SSD. The old HDD is now in my optical drive's slot.

I have a clean installation of El Captain on my SSD. Unfortunately, the guys who swapped the drives for me installed El Captain in Polish. Now I changed the OS language to English as I'm more used to it, and this is what my Finder does.

[![enter image description here](https://i.stack.imgur.com/sPxie.gif)](https://i.stack.imgur.com/sPxie.gif)

I still have an old OS installed on the other disk, which is not formatted yet. I thought that it might be by some miracle conflicting with the new installation, but Finder does this even after unmounting the old HDD.

I have absolutely no idea what to do with this, and it gets very annoying.

Has anyone had this problem before? Uncle Google brings no answers on this one :|

Answer: 
> 
> I have also removed the `~/.local/share/applications/mimeapps.list` file and the issue still persists.
> 
> 
> 

There is likely another `mimeapps.list` elsewhere on the system. You can go through the list [here](https://wiki.archlinux.org/index.php/Default_applications), or search through your system with one of the following commands: 

```
locate mimeapps.list

```

or

```
find / -name 'mimeapps.list'

```

Check for any `application/octet-stream` entries in those, and either comment them out or remove them.
Well, seems that Firefox will not fix this [issue](https://bugzilla.mozilla.org/show_bug.cgi?id=67940) but I fixed it in my way removing the `application/octet-stream=org.gnome.gedit.desktop` from my `~/.config/mimeapps.list` and using the add-on [OpenDownload²](https://addons.mozilla.org/en-US/firefox/addon/opendownload-10902/?src=userprofile) to provide me the `Run` option.

If the extension of the file being downloaded is correctly configured in the `mimeapps.list`, firefox will open **(run)** it like a charm.