I’ve got same problem yesterday, but I’m not sure if it wasn’t some kind of certbot bug - no authorization files in webroot was created (webroot plugin). Before I realized, certbot managed to create over a hundred pending authz, and now I’m getting “There were too many requests of a given type :: Error creating new authz :: Too many currently pending authorizations.” error. Is there any way to cancel/invalidate those authz, or validate them manually by creating authorization files in webroot directory?
It would theoretically be possible, yes, but you’d have to manually build some ACME requests and send them to the server. Probably not worth the hassle.
The pending authz rate limit is per account, so creating/using a new ACME account would let you bypass those limits. If you don’t have any existing certificates, you could probably just delete /etc/letsencrypt (or move it out of the way) to start from scratch. Otherwise, the certbot register subcommand together with --account should allow you to switch to a new account (consult certbot --help all for more details on usage).