Today’s issue in Linux Mint – or more specifically in Firefox Version 43.0 running under Linux Mint – is a warning message indicating that an add-on(s) has been disabled.
Two add-ons were affected – “Mint Search Enhancer” and “Stylish” – both giving similar messages (Mint Search Enhancer could not be verified for use in Firefox and has been disabled.)
Neither add-on is necessary, but there is no option to remove them from Firefox’s Tools – Add-ons window. The trick is to use either Software Manager or Package Manager, depending on the add-on to be removed.
Run Software Manager, search for “stylish” and remove mint-stylish-addon.
Run Package Manager, search for “mint search” and remove mint-search-addon.
Update to Firefox 43.0 – Kills Mint Search Enhancer
[firefox] Mint Search Enhancer 1.0 is unsigned