Hi, I am unable to install add-ons directly from the addons website, when Kaspersky Internet Security 2018 is running. If I quit Kaspersky everything is working fine. Also when Kaspersky is running, I can install the add-on after downloading the extension file to my computer. When Kaspersky is running, I am getting the message "The add-on could not be downloaded because of a connection failure" . The browser console is showing the following error 1509893684094 addons.xpi WARN Download of https://addons.cdn.mozilla.net/user-media/addons/9609/ghostery-7.4.1.4-an+fx.xpi?filehash=sha256%3A518cb53447385bf7a50f9aba2eb8cd402e1c41e279a558778203f68cf6578466 failed: [Exception... "Certificate issuer is not built-in." nsresult: "0x80004004 (NS_ERROR_ABORT)" location: "JS frame :: resource://gre/modules/CertUtils.jsm :: checkCert :: line 169" data: no] Stack trace: checkCert()@resource://gre/modules/CertUtils.jsm:169 < onStopRequest()@resource://gre/modules/addons/XPIInstall.jsm:2462 OS: Windows 10 1709 (64-bit) Firefox: 56.0.2 (64-bit) Kaspersky Internet Security 2018: 18.0.0.405 (d) Please help Sreeraj P