When you get the alert message, it means that the dated certificate has expired, much as a driver's license does.

Lucy had to get a flight physical right away because her medical certificate expired in two days.

Though the certificate allowing the ship to fly a British flag had expired, there was still an armed response.

And even if a certificate has expired, all that happens is it's expired.

One of the questioners asked, hey, when a certificate expires, what happens?

But if you suddenly go to the dark side, within a couple years this certificate will have expired.

Once the certificate has expired you will need to send a new one with your next application.

And it's like I had to run home and solve the problem because my certificate expired.

One was that the certificate itself had expired, interestingly, a few days before.

Because certificates expire, but it may sometimes be necessary to revoke them.