File Associations Keep Changing

I've had a rash of wrong file associations on Mavericks with various types of file, sometimes corrected by force-quitting (and thus rebooting) the Finder. I've run the Onyx maintenance as suggested and we'll see what happens: but meantime in both Safari and FireFox dragging an image out of a web page changes the association for all images of that type to the browser if you double-click the file (this didn't happen previously) - if you drag the image to the icon of the program you want to use it opens correctly and doesn't change the association. I suspect this is some sort of 'improvement'.

I've spoken with someone at Mozilla and it appears to be a Firefox Quantum issue only with certain versions of OSX (for example OS10.9 and OS10.10). Doesn't appear to be an issue any more with OSX10.12 or 10.13. If it is still causing an issue on 10.12 or 10.13 then it's worth doing a completely clean install of firefox.

I have the same issue. I'm pretty sure they started the day the new Firefox Quantum got released. I tried upgrading the OS (today) and the issue is the same.

So, I started experimenting, because I really really suspect Firefox there.

Computer (2011 iMac) starts, I double click to open a pdf > everything's fine.

Then I open Firefox, and drag and drop an image to the desktop: that image doesn't have a file extension anymore and the OS doesn't detect its type (since the quantum upgrade). Chrome doesn't have this bug. Once this bug is triggered I double click on a PDF, and it opens with Pixelmator or ibooks instead.

So, starting tomorrow, Firefox is out and I'll try working with Chrome. This may very well fix the issue.

I'm another with this problem. For me .JPGs keep opening in Photoshop Elements even though every time I set Preview to be the default. Worst still when I try 'Open with' Preview is not even listed so I have to click 'other' then search for the Preview app. As a workaround I've put the Preview icon on the dock and drag files to that. I'd still rather go back to the old school method of just clicking on the file though!

PS - I don't think there's any connection to which program your images default to when losing file associations.

What I mean is for the longest time, whenever I lost Preview as my default app for images, they would open in my printer's scan tool (which if you know printer software was a nightmare). I completely removed my printer's scan software and now my images default to opening in Firefox whenever they lose their association with Preview.

I checked with fsevents and it showed what is changed when dragging the file (changes take place in the PRIVATE > VAR folder) - I assume the changes being made to either com.apple.launchservices-107501.csstore or the sandbox-cache-db-shm which are causing the association changes?

CountryGirl56 wrote:

In any case it only affects the file being dragged. It doesn't change the default app for all files.

Actually that wasn't what I found: dragging a JPG from Firefox produced a file which would open in Firefox, but then every other JPG on the computer also opened in Firefox, so I had to do the 'get info' thing to get them back - at which point opening one in Graphic Converter as it should produced the notice that I was opening GraphicConverter for the first time... I also had issues of RTF file opening in Pages or TextEdit rather than Nisus Writer, MP3s opening in iTunes rather than QT player, and so on.

I've now, a bit reluctantly, moved to Chrome and so far no problems.

Actually I take back what I said. Somehow Firefox Quantum is affecting Launch Services. Aside from the aforementioned issues, a program I use on occasion to edit images was removed from the "Open with…" menu. Weird.

Thanks! I had a similar problem — xls files opening in Numbers, rather than Excel and rtf files opening in Pages, rather than TextEdit. If I logged out and back in, this restored the proper defaults. I had sort of fixed the problem by clearing down multiple Firefox windows with lots of tabs… But I was able to recreate the repeatable problem scenario on a test system and changing the sandbox value to 2, stopped the rogue behaviour.

El Capitan 10.11.6, Firefox 58.0.2, Late 2015 iMac 27".

Stopped using Adobe products. That, however, does not stop the Microsoft suite updates from changing the associations. Instead of Preview, suddently Grab is used to open JPGs. Instead of Preview for PDFs, MS Word comes ups (reeeeeaaaaalllll slow to open nothing but code.

Running 10.3.3 and latest MS products for Mac.

Instead of dragging the image from Firefox, try right/control clicking the image and choosing "Save Image As…". You shouldn't have the same problem.

Make sure you have a good backup in case.

Just now uninstalled Firefox Quantum. Will see what happens and report back.

Uninstalling did Firefox Quantum resolve the problem for me. Have restarted computer a couple of times.