Until Bug 653410 is fixed, the best workaround I can come up with is to detect when safe mode is launched and handle it in the best way fit for your particular purposes. This may mean killing the Firefox process and launching again, or it may mean warning the user, or both.
When Firefox is launched into safe mode, it writes "LastVersion=Safe Mode" to its compatibility.ini file in its profile directory. An example C# function to watch for this is given below.
private void watchSafeMode()
string profiles = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), "Mozilla", "Firefox", "Profiles");
string defaultProfile = Directory.GetDirectories(profiles, "*default*");
safeModeWatcher = new FileSystemWatcher(defaultProfile, "compatibility.ini");
safeModeWatcher.NotifyFilter = NotifyFilters.LastWrite;
safeModeWatcher.Changed += delegate(object s, FileSystemEventArgs e)
if (File.ReadAllText(e.FullPath).Contains("LastVersion=Safe Mode"))
// safe mode!
System.Diagnostics.Trace.WriteLine("safe mode detected!");
// TODO kill Firefox and launch again, or whatever makes sense for you
safeModeWatcher.EnableRaisingEvents = true;
// TODO Dispose safeModeWatcher when done