Is this the extension? If it is, it was Last updated Jan 18, 2023 https://addons.mozilla.org/en-US/firefox/addon/nethunt-crm-in-gmail/?utm_source=addons.mozilla.org&utm_medium=referral&utm_content=search Thanks for the screenshot, but I don't see a Firefox issue, Google is blocking it. How about asking either Google and or the dev team of the extension for assistance. Provide details on what you're doing until you get the error. It would be impossible for us to replicate because we don't have access