IO Error The Network Adapter could not establish the connection

Question

I am new to Oracle  and am trying to run a simple example code with Java  but am getting this error when executing the code   I am able to start up the listener via CMD and am also able to run SQL Plus  Can anyone give me a hand and tell me what I might be doing wrong   Update  I am using JDBC   Database is local  and I actually had it working but it stopped working just today  I m not really sure why though  Would you mind giving me some procedures to follow by since I don t know much

User · Answer

In my case  I needed to specify a viahost and viauser  Worth trying if you re in a complex system

User · Answer

I figured out that in my case  my database was in different subnet than the subnet from where i was trying to access the db

User · Answer

Most probably you have listener configured wrongly  the hostname you specify in connection string must be the same as in the listener   First check the Firewall and network related issues   Check if Oracle Listener service is available and running  If not you may use Oracle Net Configuration Assistant tool to add and register new listener   If the above steps are ok then you need to configure Oracle Listener appropriately  You may use Oracle Net Manager tool or edit     ORACLE HOME  network admin listener ora    file manually    There are 2 options that need to be considered carefully  Listening Locations associated with the Listener     Hostname IP  and Port in Listening Location must exactly match the ones used in the connection string    For example  if you use 192 168 74 139 as target hostname  then there must be Listening Location registered with the same IP address    Also make sure the you use the same SID as indicated in Database Service associated with the Listener   https   adhoctuts com fix-oracle-io-error-the-network-adapter-could-not-establish-the-connection-error

User · Answer

I was having issues with this as well  I was using the jdbc connection string to connect to the database  The hostname was incorrectly configured in the string  I am using Mac  and the same string was being used on Windows machines without an issue  On my connection string  I had to make sure that I had the full url with the appending  organizationname com  to the end of the hostname   Hope this helps

User · Answer

I had the same problem  and this is how I fixed it   I was using the wrong port for my connection   private final String DB URL     jdbc oracle thin  localhost 1521 orcll      1521 my wrong port    go to your localhost  my localhost address     https   localhost 1158 em   login     user name  password connect as --  normal  Below  General  click on  LISTENER localhost look at you port number  Net Address  ADDRESS  PROTOCOL TCP  HOST localhost  PORT 1522   Connect to port  1522  Edit you connection change port 1521 to 1522    done

User · Answer

Either    The database isn t running You got the URL wrong There is a firewall in the way     This strange error message is produced by Oracle s JDBC driver when it can t connect to the database server   Network adapter  appears to refer to some component of their code  which isn t very useful  Real network adapters  NICs  don t establish connections at all  TCP protocol stacks do that  It would have been a lot more useful if they had just let the original ConnectException be thrown  or at least used its error message and let it appear in the stack trace

User · Answer

Another thing you might want to check that the listener ora file matches the way you are trying to connect to the DB  If you were connecting via a localhost reference and your listener ora file got changed from   HOST   localhost   to  HOST   192 168 XX XX   then this can cause the error that you had unless you update your hosts file to accommodate for this  Someone might have made this change to allow for remote connections to the DB from other machines

User · Answer

I had this error when i renamed the pc in the windows-properties  The pc-name must be updated in the listener ora-file

User · Answer

To resolve the Network Adapter Error I had to remove the - in the name of the computer name

User · Answer

For me the basic oracle only was not installed  Please ensure you have oracle installed and then try checking host and port

User · Answer

Just try to re-create connection  In my situation one of jdbc connection stopped working for no reason  From console sqlplus was working ok   It took me 2 hours to realize that If i create the same connection - it works

[java] IO Error: The Network Adapter could not establish the connection

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