Jimmy Breck-McKye

Developing opinions

Disabling Firefox Safe Mode

A couple of weeks ago I faced a problem where Firefox’s “Enter Safe Mode” dialog was causing problems for a Selenium test suite I was trying to run.

Basically, Firefox would sometimes throw the dialog and my test framework (naturally) wouldn’t be able to dismiss it without my help. This meant the Firefox instance stayed open, so if I tried running the suite again, I’d get an exception:

org.openqa.selenium.WebDriverException: Unable to bind to locking port 7054 within 45000 ms

Annoying. To me, it seemed the simplest solution was to merely disable Safe Mode entirely, as I would never need it during a test. Rummaging around in Stack Overflow and the Mozilla bugtracker, I found this ticket that proposed I could either:

  • set an environment variable, MOZ_DISABLE_SAFE_MODE, or
  • pass a config setting, maxResumedCrashes = -1 to about:flags or a user profile

According to the webdriver documentation, you can set a custom user profile flag fairly easily with profile.setPreferences("key","value")

Disabling Safe Mode was simple:

profile.setPreferences("toolkit.startup.max_resumed_crashes", "-1");

If you’ve got the same problem, you might want to give it a try.