Let's Encrypt SSL certificates showing error: ERR_CERT_COMMON_NAME_INVALID
Problem
Users are currently facing an issue in domains that are using Let's Encrypt's SSL certificate on older devices like Windows 7. This problem is due to expiration of the DST Root CA X3 Cert from Let's Encrypt. DST Root CA X3 Expiration (September 2021)
Reason
Let Encrypt SSL certificate was using DST root X3 (expired September 30, 2021), they are now using ISRG root X1. Since Microsoft's support for Windows 7 ended on January 14, 2020, so Windows 7 does not receive software updates. This means that older devices do not trust ISRG Root X1 and start receiving certificate warnings when visiting sites that use Let's Encrypt certificates.
Workaround
We recommend you to update to Windows 10 or use paid SSL or use Cloudflare SSL.
Wednesday, October 6, 2021
