Hi Folks,
If you are suddenly encountering problems with TLS certificate validation when connecting to Atlas, this is likely due to older root certificates used by Let’s Encrypt expiring on Sept 30, 2021. MongoDB Atlas uses Let’s Encrypt to sign Atlas cluster TLS certificates.
This validation issue is on the client side of the connection, not the server. Your Atlas cluster certificates are still valid, but your local trust stores do not contain the new root certificate required for verification.
Common root certificates are generally included in O/S updates, but in some cases you may need to manually update trust stores used by your O/S or application environment.
For more information, please see: Which certificate authority signs MongoDB Atlas cluster TLS certificates?.
Regards,
Stennie