Mozilla will no longer support Firefox extensions that use old and unstable technology starting this summer. The affected extensions use a technology called "Binary XPCOM".
"Binary XPCOM is an old and fairly unstable technology that a small number of add-on developers have used to integrate binary libraries into their add-ons, sometimes to tap into Firefox internals", Mozilla's Jorge Villalobos writes on the Mozilla website.
This method can cause stability issues. Meanwhile, better technology is available and Mozilla calls extension developers to switch to using these. According to Villalobos the developers that use XPCOM should update their extensions as soon as possible to prevent compatibility issues.
Starting from Firefox 40, scheduled for August this year, these old extensions with XPCOM code will no longer be supported.
