LetsEncrypt is a free SSL provider that you can use to get free SSL certificates for your website and other web services. The older protocol that LetsEncrypt uses to issue SSL certificates - which they call is called ACMEv1 - is being phased out in favor of the newer ACMEv2 protocol. This is causing some applications that use LetsEncrypt ACMEv1 to create or renew SSL certificates to fail. For Vivio clients, this will mostly affect LetsEncrypt on Virtualmin servers.
Timeline for LetsEncrypt to phase out ACMEv1
November 2019: LetsEncrypt will stop allowing new account registrations through their ACMEv1 API endpoint. Existing accounts will continue to function normally.
June 2020: Lets encrypt LetsEncrypt will stop allowing new domains to validate via ACMEv1.
Starting at the beginning of 2021: LEts encrypt LetsEncrypt will occasionally disable ACMEv1 issuance and renewal for periods of 24 hours, no more than once per month. The intention is to induce client errors that might encourage subscribers to update to clients or configurations that use ACMEv2.
June 2021: Lets Encrypt LetsEncrypt will entirely disable ACMEv1 as a viable way to get a Let’s Encrypt certificate.