For those having Problems! Rated 5 out of 5 stars
1.Restart as directed after install,then restart again to ensure the add-on compatibility checking was disabled.
2.If you want to use and test your incompatible add-ons, this is "important""DO NOT ENABLE" the add-on compatibility checking in the warning dialog in the Add-on window by accident.
3.To disable add-on compatibility checking onced enabled, type about:config in the address bar and press Enter.
1. Do Filter Search: extensions.acr.firstrun
2. Set Value to: True
3.Then restart twice as you did in step 1.