After updating firefox did one of your favorite addon’s stop working because its incompatible with your updated version of Firefox. Here’s an addon called Nightly Tester Tools that lets you enable the disabled incompatible extensions.

After installing Nightly Tester Tools, go to Tools > Add-Ons > right click on any disabled plugins because of incompatibility and select “Override Compatibility”.   ( OR ) You can also override all incompatibilities of all incompatible plugins by clicking on “Override all Compatibility”.

Its advisable to override each plugin one by one to identify any problems like hangs, crashes, memory leaks, data corruption or other problems that rise after overriding incompatibility.

NOTE : Forcing an incompatible extension to install is risky. There are many cases where Firefox will stop working completely or behave incorrectly because an incompatible extension is being forced to work where the author never intended.