Are you able to update Kaspersky? According to users on Kaspersky's forum last week, a release compatible with Firefox 44 is available but you might have to install it manually if auto-updating is not working. Download page: http://www.kaspersky.com/product-updates You want this version: 16.0.1.445 Forum thread: http://forum.kaspersky.com/index.php?showtopic=344608 After updating Kaspersky, exit out of Firefox and start it up again to prompt Firefox to discover the updated extension. Then check whether you can enable it on the Add-ons page. Either: * Ctrl+Shift+a * "3-bar" menu button (or Tools menu) > Add-ons In the left column, click Extensions. Then check for Kaspersky on the right (it may be at the bottom). Success?

=== Anti Virus Protection === It is often the case with this sort of issue that the main and most important security component & feature the Anti Virus software; if updated; continues to function properly. === Secondary Features & Components === What is most likely to temporarily be a problem is secondary features and software. Components that may be of only speculative value such as protection from phishing and malware sites - something already built into Firefox and enabled by default * [[How does built-in Phishing and Malware Protection work?]] ---------- === Please try to fully describe your Kaspersky software === Just a tip for anyone asking about problems with Kaspersky products. It helps us when trying to give good answers, if you please list carefully and fully all the Kaspersky products you have installed: giving their full name and version numbers. Please then say what works and what you get problems with. I note Kaspersky offers a wide variety of Software * Free trials: e.g. http://www.kaspersky.co.uk/free-trials * Home http://support.kaspersky.com/#s_tab2 *Small Office [http://support.kaspersky.com/#s_tab2 tab3] & Business [http://support.kaspersky.com/#s_tab4 tab4] products * Free tools [http://support.kaspersky.com/#s_tab5 tab5] It appears for instance that "''Kaspersky Protection 4.6.2.23.1''" may be part of "''Kaspersky Internet Security 2016''" [http://forum.kaspersky.com/index.php?act=Print&client=printer&f=4&t=344648 .] === Firefox's Addon Signing === This is a new feature being introduced to help protect users of addons and to increase Firefox's security. For further info see * '''[[Add-on signing in Firefox]]''' * (Feb & April 2015) **_{[https://blog.mozilla.org/addons/2015/02/10/extension-signing-safer-experience/ Introducing Extension Signing: A Safer Add-on Experience]} ** _{[https://blog.mozilla.org/addons/2015/04/15/the-case-for-extension-signing/ The Case for Extension Signing]}