Over deze add-on
Since a couple of Firefox versions checkCompatibility doesn't work anymore because it was not compatible itself.
I just edited some files to make it compatible with every Firefox version again.
Original Addon here: https://addons.mozilla.org/de/firefox/addon/checkcompatibility/
Sorry guys after the release of Firefox 57 this addon is not gonna work up-to-date versions anymore.
With the Firefox 57 update Mozilla team wants to do what this addon is doing all along.
They changed the addon system and because of that all of the old addons are dead.
The new system does not offer that much change in the system and because of that the hardcore systemintegration addons will be not possible.
But on the bright sight there will be no compatibility problems and any add on malwares anymore.
R.I.P old Addons 14-Nov-2017