Lock Preferences firefox 43.0.4 mozilla.cfg won't load

Hi,

I'm currently using Portable Firefox 43.0.4. For ease of use, before deploying the new mozilla.cfg file, I always use my trusty portable version to test out the new configuration file.

Since switching to 43.0.4, the file is not being picked up. I've placed the mozilla.cfg file inside portablefirefox/app/firefox. This is the content:


lockPref("general.config.filename","http://somerandomsite.com/theJSfile.js");


What am I doing wrong? This used to work in firefox 25 but no longer works with 43.0.4,.

Thanks for helping,

Art