That is unfortunate, there have been important security updates since 30. Note that you can always download a .tar.gz copy from:

• https://www.mozilla.org/en-US/firefox/all/

Unzip it in your home directory. It should be precompiled so you don't need to do anything else but run it.

As to your dictionary, I remember needing to install a Canadian English dictionary in order to use it - what happens if you uninstall that in:

• Tools > Add-ons > Dictionaries

You can also enter about:preferences in your address bar, go to Content, and "Choose". From there you can reorder your languages and see if that changes your default dictionary.

What Linux distribution do you have?

Note that Firefox might be getting confused if you have (Hunspell) dictionaries installed that have an underscore in the name instead of the dash (en_US versus en-US).

• /usr/share/hunspell/
• /usr/share/myspell/

@CoryMH:

I checked about:preferences, my preferred content language is en-us. I don't see a way to change my dictionary through that part of the interface.

I also checked Tools -> Add-ons -> Dictionaries. No Canadian dictionary is even installed there.

I will try the latest Firefox from the page you lined, and report back.

Thanks!

@cor-el: this is Xubuntu 13.10.

I'm not sure how to debug the problem you mentioned. There are a bunch of dictionaries under those directories.

@CoryMH: downloaded and executed Firefox 33.0.1 from the link you provided, and the problem is now gone.

Thanks. Marked as "solved".

Ubuntu 14.10 and Firefox 37, I still have this. I vaguely seem to remember it got fixed, but if so it came back.

… and I seem to have not only fixed it, but discovered the reason. Yay me. I'll post this comment anyway, in case someone else gets here via google.

This is what I was about to post:

The commonly offered fix, of deleting all dictionaries but the one I want, is unacceptable for me for two reasons: first, there's no way to delete pt_PT separately from pt_BR, either through apt or about:addons. Second and more importantly, I do need to keep many dictionaries, since I often type in many different contexts: en_GB, en_US, de_DE, and pt_BR. (Also ja_JP, but there's no spell check for that, so one less thing to worry about.)

There seems to be no rhyme or reason to which dictionary it picks, except it's consistent. It was always en_CA, after I uninstalled that, it's now always pt_PT.

Then I had a good search through about:config and found the services.sync.prefs.sync.spellchecker.dictionary and services.sync.prefs.sync.layout.spellcheckDefault settings. So on a hunch, I selected en_GB, forced a sync, quit Firefox, and opened it again… presto, it's en_GB. I think the problem was sync: when I selected a language locally, it didn't sync that preference to the server, and next time I started, it picked up whatever was stored in the server.

You can toggle such services.sync.prefs.sync.* prefs to false to prevent Firefox from synching them across devices.