On September 30, 2021, Letsencrypt’s DST Root CA X3 cross-sign (by IdentTrust) root certificate expired and was replaced with Letsencrypt’s own ISRG Root X1 CA root certificate. I’ll outline how Centmin Mod LEMP stack handled the Letsencrypt’s DST Root CA X3 certificate expiration for CentOS 7.x operating systems.