In this article, we’ll show you what to do when you see the warning. If it happens once or twice, it’s not too much of a problem, but if it happens on almost every website you want to visit, it’s a serious inconvenience. If the certificate for that connection has expired or is invalid, macOS will warn you and ask you whether you want to continue, inspect the certificate, or cancel. The certificate in question is one used by your Mac to validate that a connection you are trying to make to a server is secure. You might have noticed that when you visit some websites on your Mac, you get a warning that says, “the certificate for this server is invalid” and asks you what to do next. But to help you do it all by yourself, we’ve gathered our best ideas and solutions below.įeatures described in this article refer to the MacPaw site version of CleanMyMac X. So here's a tip for you: Download CleanMyMac to quickly solve some of the issues mentioned in this article.