Same thing started happening to us this morning.

Ran the setup /force (and reboot) and the problem still exists.

I can't get into 2019 and I really need to. Like now.

Ran the WebSetup /force again (with reboot) and now things appear to be working.

Not sure if there was an issue with an update or "behind the scenes", but '21 is working again.

Hello! Please try the steps on this link and let me know if that helps. Thanks! 

https://accountants.intuit.com/community/lacerte-tax-news-updates/discussion/action-required-securit...