I’m using “Full” end-to-end encryption setting in Cloudflare. My site is proxied through Cloudflare. The certificate on my origin server has expired, yet visiting the site via HTTPS is working perfectly.
According to this answer, Err_cert_date_invalid the cert validity doesn’t matter:
If your origin certificate expired, maybe regular “Full” SSL will work since it’s not necessarily checking for a valid SSL certificate.
Why does Cloudflare ignore the expiration date of the certificate on the origin? What information does it need from the certificate then?