I am trying to install a Firefox extension into Firefox 3.6.13 under OS X 10.5.8, and I keep getting an error message:


Firefox could not install the file at

because: Download error -228

I have read this and found it unhelpful. My cache is 500 MB and ~/Library/Caches/TemporaryItems is writable:

[jnet@Stan ~]$ ls -la ~/Library/Caches/TemporaryItems
total 16
drwx------    5 jnet  jnet   170 Jan 27 20:51 .

Any idea how I can correct this?

2 Answers 2


Try to rightclick and save the .xpi file. If you can do it, you can execute it or drag it to Firefox to install it.

  • OK, this did work, thanks. I couldn't even download the extension in Firefox but I could via wget. I'd still like to solve the actual problem though!
    – Josh
    Jan 28, 2011 at 3:02

Now that you've downloaded the .xpi file to your computer, try opening a Finder window at its location and the Firefox add-on manager window simultaneously, and then dragging the .xpi file to the add-on manager window.

  • Right I can download and install the xpi files, but that's not my question. What I want is to have them install automatically like they're supposed to. Or to make updates work. I.E. how do I stop the above error from appearing?
    – Josh
    Feb 16, 2011 at 21:14

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