I m trying to install HDP 2.6.4 using ambari ambari-2.5.0.3 in RHEL 7.5 using jdk1.8.0_101 and postgresql-9.5.8. I am able to install ambari agents and ambari server in all hosts. While registering all host in ambari ui all host registration is getting failed except ambari-server host. Also verified /etc/hosts in all servers ,hostname are correct and i am able to telnet the ambari server from all agent servers. my openssl verion- openssl version -v OpenSSL 1.0.2k-fips 26 Jan 2017 I am adding agent log below please check. INFO 2018-06-11 14:55:42,409 NetUtil.py:67 - Connecting to https://amabri_server_host:8440/ca ERROR 2018-06-11 14:55:42,487 NetUtil.py:93 - [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:579) ERROR 2018-06-11 14:55:42,487 NetUtil.py:94 - SSLError: Failed to connect. Please check openssl library versions. Refer to: https://bugzilla.redhat.com/show_bug.cgi?id=1022468 for more details. WARNING 2018-06-11 14:55:42,488 NetUtil.py:121 - Server at https://amabri_server_host:8440 is not reachable, sleeping for 10 seconds... ... View more