Please verify if you have followed all the below prerequisites before adding WebLogic monitor :
1. HTTP port of WebLogic server should be accessible from Applications Manager installed machine.
a. Check if the WebLogic host and port is accessible via TELNET.
b. Check if there is any firewall between WebLogic Host and the Applications Manager machine. If this is the case, then open WebLogic host and port in the Applications Manager side.
2. For monitoring your WebLogic server, the user need to have 'Administrator' privileges.
To assign 'Administrator' privilege to a user in WebLogic, refer here
3. Applications Manager does a JNDI lookup to get the Mbeanserver. So please check whether the configured user has the permission to do a JNDI lookup
a. Access the JNDI Tree security policy from WebLogic Admin console by navigating to Admin console -> Environment -> Servers -> <Required server> -> View JNDI Tree-->Security-->Policies-->Methods.
b. Under Methods, it should be 'ALL'.
4. Make sure the same Host/IP which is configured in Listen Address in WebLogic server is used while adding the monitor in Applications Manager.
You can find the host/IP address of the same under Environment -> Servers -> <Required server> -> Configuration -> General -> Listen Address field.
5. T3 connection is should be possible from Applications Manager machine to WebLogic server.
a. Enable T3 Tunneling by following the steps mentioned here
b. Check if the webLogic server is responding to T3 ping. Try to execute the below command from some other installation of WebLogic machine ( <WebLogic_HOME>/wlserver/server/lib directory ) to this WebLogic machine.
6. Check whether the /etc/resolv.conf file (in windows it is Windows\System 32\drivers\etc\hosts file) in the Applications Manager Machine has correct domain.
a. Make sure there is no incorrect resolution present for WebLogic server host.
7. Check whether Filters are enabled in Weblogic domain, and Applications Manager Host/IP is restricted.
- <mydomain> -> Security -> Filter
8. The jars might be either corrupted or outdated.
For version 12 and above, some WebLogic servers requires fullclient jars. Please use the jars below :