Unanswered: JDBC error : The Network Adapter could not establish the connection
I started a JSP page on Oracle 18.104.22.168 and I received this message :
java.sql.SQLException: Io exception: The Network Adapter could not establish the connection
..but I restarted a listener and then JSP page worked correctly!
(Listener detect only 1 service handler)
...but later I started a command : lsnrctl status ....and Listener detected
3 service handlers...and the same JSP page didn't work, because :
java.sql.SQLException: Io exception: The Network Adapter could not establish the connection!
I wonder if this is caused by dynamic listener registration overwriting a static registration. Compare the address info for your SID in file listener.ora to the local_listener parameter in file initSID.ora. This init.ora param is only necessary if your listener is not using all of the default attributes, like port=1521 and protocol=TCP. I can imagine if any of the attributes in parameter local_listener are incorrect, or need to be set but are not set, then Oracle will overwrite your in memory values established from file listener.ora.