User Agent: Mozilla/5.0 (X11; Ubuntu; Linux i686; rv:20.0) Gecko/20100101 Firefox/20.0 Build ID: 20130329030848 Steps to reproduce: (several iterations) Set spellchecker.dictionary (in about:config) to 'en_US'. Actual results: After update, or sometimes for no apparent reason, setting is changed to 'en_GB'. Expected results: The setting should have remained the same. NOTE: content-prefs.sqlite is also changed. Setting every value instance of 'en_GB' to 'en_US' does not solve the problem. Removing every file containing 'en_GB' does not solve the problem. It appears to be embedded elsewhere.

I have seen this problem or others like it reported in various places. In all cases the instances I read about have been dismissed as non-reproducible or fixed. I want to assure you that the problem continues to occur with great regularity on this machine.

Appears to duplicate 728069.

It sounds a little different. In bug 728069, the setting keeps reverting from people's native languages to en-US. Here it's the opposite: Gordon set it to en-US but it's reverting to en-GB. Probably similar underlying problem, though.

I may have discovered the source of the problem. In poking around my system, I discovered that Firefox had three language pack add-ons, one for English (GB), one for English (South African) and one for Chinese. I did not install these add-ons and would have no reason to, so I assume they came with the program. I ensured that they were all disabled and that my spell-checker preference has been once again set to 'en_US' in both content-prefs.sqlite and prefs.js. I will see what happens. Note that I am running Ubuntu (12.4) which comes with Firefox, and that I probably downloaded the original installation file(s) from Canonical (in SA).

That's not "the source" of the problem. The whole point of having a selector is to be able to have multiple dictionaries installed, and I intentionally have Spanish dictionaries installed, but the text box keeps resetting the default.

In some further research on this problem, I've observed that it appears to occur only when plugin-container is running (to play flash animations, I assume) and a web site specifying en_GB has been accessed. The 'en_GB' first appears in sessionstore.js, Several minutes later it shows up in content-prefs.sqlite, and shortly after that in prefs.js.

I'm experiencing the issue with es_CU, but plugin-container is always running for me as well (Facebook pulls in Flash for some unclear reason). I've noticed that visiting a comments thread on Fark.com reliably triggers the bug in Facebook's text boxes.

Closing this bug as per bug 1073827, comment #33. If you want to reopen it, please present a reproducible test case.