The 'no pg_hba.conf entry ... no encryption' error on RDS Postgres is an SSL mismatch, not a security group problem. Fix it with rds.force_ssl: create a new parameter group for your Postgres version, set rds.force_ssl to 0, attach the parameter group to the instance, and reboot. The client was connecting without SSL while the instance required it, which is why adding IPs to security groups changed nothing.

Context: Stack Overflow #76899023 (accepted answer, 147 votes): I need assistance as I'm having trouble connecting to a managed Postgres database on RDS. I'm encountering the following error message: "no pg_hba.conf entry for host '16.151.149.51', user 'analytics', database 'database', no encryption" I have confirmed that encryption is functioning properly, and I've also added the IP to the security groups. What steps should I take to resolve this issue?