If you are using ZeroSSL with Caddy and are having trouble issuing or renewing your certificate, check your ZeroSSL Status. https://status.zerossl.com/
I checked the ZeroSSL Status and now the ZeroSSL ACME API is down a lot. It looks like this response has been getting worse for a few days. https://status.zerossl.com/8200003/2021/06
Edit: This issue seems to have been addressed. You can check the latest server status from the link above.
I received an announcement from ZeroSSL. If you are using ZeroSSL with Caddy, you will need to take action at the Caddy or user level. This will be done in the GitHub Issue.
From the ZeroSSL website, ZeroSSL will be maintained for 6 hours after this.
Even if there are reports of troubles that cannot be issued, it is a problem on the ZeroSSL side.
Perhaps this maintenance will change some certificates.
(Edit: June 12, 2021 (Japanese Time: June 13 morning))
Some ZeroSSL were revoked on June 11, 2021.
We have already seen the related posts.
However, Firefox is mainly affected. Chrome also delays sending a revoked certificate error.
Edge (Chromium based) are not affected by this.
It may not have been noticed by you for a while.
Supports revoked certificate renewal in Caddy v2.4.2.
But their Caddy developers haven’t been able to test these.