Firefox 39 crashing

I already asked this on Firefox support but still no anwer so maybe someone here knows how to fix this.

After I updated Firefox to version 39 I can't use it at all, it crashes all the time, I couldn't even write this question from Firefox. I clicked on "Refresh Firefox" button, also I restarted with addons disabled, also I reinstalled Firefox but none of that helps. Crashes are random, after 5-6 minutes of browsing.

You can see crash reports here: https://support.mozilla.org/en-US/questions/1071421

EDIT: I installed developer edition of Firefox and no crashes so far

After many attempts, I have a fix for this. The problem lies with Firefox version 39 and the Flash plugin. Either the Adobe or the Pepper flash.

What I have done is totally delete the flash plugins, install the Pepper flash, and download Firefox 39 from Mozilla, and overwrite Firefox 39, which came from the Ubuntu repositories.

The very first thing is to delete all Adobe flash installations

dpkg-query -l | egrep 'flash|fresh'

Now delete these with the purge option, using the file names returned from the dpkg-query command:

dpkg --purge <file_names>

Now you can install the pepperflash from webupd8:

sudo apt-get install pepperflashplugin-nonfree
sudo add-apt-repository ppa:nilarimogard/webupd8
sudo apt-get update
sudo apt-get install freshplayerplugin

Now you will need to download the latest version of Firefox from Mozilla, as the version from Ubuntu seems to have issues. First step is to backup, for just in case something breaks:

sudo tar -cvPpf ~/Firefox-backup.tar /usr/lib/firefox*
sudo wget -P /usr/lib/firefox https://download-installer.cdn.mozilla.net/pub/firefox/releases/39.0/linux-x86_64/en-US/firefox-39.0.tar.bz2
sudo tar -C /usr/lib/ -jxvf /usr/lib/firefox/firefox-39.0.tar.bz2

Now you should be able to start Firefox and watch video without the constant crashes.