We have fully turned off the ACMEv1 API as a viable way to get a Let’s Encrypt certificate. Users will see this message when they attempt to issue a certificate with the ACMEv1 API:
ACMEv1 is deprecated and you can no longer get certificates from this endpoint. Please use the ACMEv2 endpoint, you may need to update your ACME client software to do so.
If you have a certificate issued from the ACMEv1 API it will continue to work until it expires. Before it expires, you should update your clients to use ACMEv2. If you need help updating your client software please look at Help thread for ACMEv1 EOL (June 2021) - Returned ACMEv1 is Deprecated Error Message
Prior to our final cutoff, only 0.6% of Let’s Encrypt issuance was done via ACMEv1. In January 2020, we started sending notifications about our ACMEv1 deprecation plan and timeline to subscribers who were using ACMEv1 and had an e-mail associated with their account. Since those e-mails started, we’ve done brownouts at each stage of deprecation to induce client errors for users that were not receiving e-mails. Additionally, we’ve been updating this thread with all the deprecation progress. Thanks to our subscribers, community, and many client developers who have worked with us along this journey to create a smooth transition to ACMEv2. We are now able to fully serve our subscribers with a version of the protocol that matches the finalized RFC and do not anticipate making any additional protocol switches.