Users need to update their browsers to Firefox 128 (released in July 2024) or later and ESR 115.13 or later for ‘Extended Support Release’ (ESR) users.

“On 14 March a root certificate (the resource used to prove an add-on was approved by Mozilla) will expire, meaning Firefox users on versions older than 128 (or ESR 115) will not be able to use their add-ons,” warns a Mozilla blog post.