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Io exception: Oracle Error ORA-12650 in Oracle Cloud

I have been using Oracle cloud PAAS linux server for my DB machine (Oracle 11g) and having linux application server where i can run all my Java applications.
Assume i have spring based web application which can connect cloud DB machine. I have tried to access the schema in Toad for oracle, it is working as expected but when i try to hit the DB for retrieving the data from application it gives below error.
java.sql.SQLException: Io exception: Oracle Error ORA-12650
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:112)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:146)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:255)
at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:387)
at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:420)
at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:165)
at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:35)
at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:801)
at java.sql.DriverManager.getConnection(DriverManager.java:582)
at java.sql.DriverManager.getConnection(DriverManager.java:154)
at GetConnection.main(GetConnection.java:35)
I have also tried to extend the service access from SID to service name in DB machine. Still give same error. Same code works fine in another cloud machine, which was set by us. But this cloud machine was done by oracle team and most of the things are by default.
Please share your suggestion to fix this issue.

This issue is because of Oracle DB machine encryption ENCRYPTION_SERVER settings. As i understood which is default and set it to enabled, when we set it to disabled or comment the line then application will work as expected. Below is the file name for reference,
Filename : sqlnet.ora (We have to disable ENCRYPTION_SERVER settings)
File Location : ../oracle/product/11.2.0/dbhome_1/network/admin
Hope this helps some one.!

It did not help me at all. Actually I followed your solution and I ended up having another error more critical and serious than the one trying to solve.
Let me explain. First of all the value "disabled" that you mentioned is not even an accepted value for this parameter. According to Oracle (Oracle Docs) these are the accepted values that anyone can use:
SQLNET.ENCRYPTION_SERVER
Purpose
To turn encryption on for the database server.
Default
accepted
Values
accepted: to enable the security service if required or requested by the other side.
rejected: to disable the security service, even if the required by the other side.
requested: to enable the security service if the other side allows it.
required: to enable the security service and disallow the connection if the other side is not enabled for the security service.
Example
SQLNET.ENCRYPTION_SERVER=accepted
In my case being a 12c Oracle Cloud database the default was set to "required" giving me the error "Io exception: Oracle Error ORA-12650" when trying to start my application.
Setting the parameter to "accepted" solved the issue and managed to start my application.
In case you still get the error you can also set the following parameter to accepted:
SQLNET.CRYPTO_CHECKSUM_SERVER = accepted
if you see that in your sqlnet.ora the value is set to "required".
Please have in mind that my application as well as my OCI setup are for testing purposes only and they are not intended to be used in production environment. Setting the value of SQLNET.ENCRYPTION_SERVER and SQLNET.CRYPTO_CHECKSUM_SERVER to "accepted" will significantly lower your Database's security making it vulnerable to any attacks from any application that has access to it. The best case scenario is to modify your application to use the ENCRYPTION as "required".

Downgrading the OJDBC jar to version7 also works - Replace higher version(ojdbc14.jar was the culprit in my case) with ojdbc7.jar in your dependency files

Nifi-1.0.0 and Crate.IO

Crate database offers a jdbc driver through which I should be able to connect to Crate from Nifi using DBCPConnectionPool controller service. So I did that, I get a connection, the ConvertJSONToSQL processor is able to get the columns from the Crate database but when I get to the PUTSql processor I get the following error:
FlowFileHandlingException: transfer relationship not specified
The thing is that I have a SUCCESS, FAILURE, RETRY relationship defined. It just throws a ProcessException in the onTrigger() method.
Any ideas how can I make it work ?
As soon as the jdbc driver is compatible it should work, but ...

I believe this is a bug in PutSQL that is hiding an issue either in the JDBC configuration, SQL statement, or something else. Using the standalone JDBC driver with valid SQL INSERT statements, I was able to PutSQL working with Crate.
Can you double-check your connection information and SQL statement(s)? Also if you can reproduce and want to share the SQL and/or connection info (JDBC URL, e.g.), please feel free, it could help get to the bottom of the PutSQL bug that is hiding another issue.

Error connecting to Oracle database using JDBC [duplicate]

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.

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.)

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

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.

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.

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

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/

IO Error: The Network Adapter could not establish the connection (CONNECTION_ID=iKQM6lBbSLiArrYuDqud8A==)
if you are facing this issue
1- make sure you have downloaded oracle databases like oracle 11g,19c, 21c, or any latest databases.
2- search for services in your computer or type win+r then services.mis then search for oracleservice you will find orcl or xe or any other sid like oracleserviceorcl;
after that you can test your connection using sql developer, sql plus or cmd

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

In my case, I needed to specify a viahost and viauser. Worth trying if you're in a complex system. :)

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

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.

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.

Database Error : Vendor 20

When I'm connecting with database it was showing following error
An error was encountered performing the requested operation:
The Network Adapter could not establish the connection
Vendor code 20
I think it was due to problem with my classpath i tried to fix it but not succeeded
my classpath is :
E:\app\JamesPJ\product\11.2.0\dbhome_1\jlib\orai18n.jar;E:\app\JamesPJ\product\11.2.0\dbhome_1\jdbc\lib\ojdc6_g.jar;E:\app\JamesPJ\product\11.2.0\dbhome_1\BIN;C:\Program Files\Java\jdk1.7.0_09\bin;C:\Users\JamesPJ\Documents;E:\app\JamesPJ\product\11.2.0\dbhome_1\jdbc\lib;E:\app\JamesPJ\product\11.2.0\dbhome_1\jlib;E:\app\JamesPJ\product\11.2.0\dbhome_1\jdbc\lib\ojdbc6.jar;E:\app\JamesPJ\product\11.2.0\dbhome_1\oc4j\jdbc\lib\orai18n.jar;E:\app\JamesPJ\product\11.2.0\dbhome_1\oc4j\jdbc\lib\ocrs12.jar
If any one know the solution please help me
Thanks in advance.....

If you are using oracle then make sure Oracle Listener is started.

The Network Adapter could not establish the connection
I think you have network related problem. So at least you have specified database connection endpoint incorrectly or database is down.

IOException : The network adapter could not establish the connection

I am trying to connect to an Oracle database from my Java application. I am using oracle.jdbc.driver.OracleDriver, Version : 0/1 to connect to the database. But DriverManager.getConnection() is giving me the "The network adapter could not establish the connection". This is not happening evertime. Its happening sometimes only, may be once in 8-10 times. The stack trace am getting is :
Driver Class : oracle.jdbc.driver.OracleDriver, version 0/1
java.sql.SQLException: Io exception: The Network Adapter could not establish the connection
at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:134)
at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:179)
at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:334)
at oracle.jdbc.ttc7.TTC7Protocol.handleIOException(TTC7Protocol.java:3678)
at oracle.jdbc.ttc7.TTC7Protocol.logon(TTC7Protocol.java:352)
at oracle.jdbc.driver.OracleConnection.<init>(OracleConnection.java:365)
at oracle.jdbc.driver.OracleDriver.getConnectionInstance(OracleDriver.java:547)
at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:347)
at java.sql.DriverManager.getConnection(DriverManager.java:316)
at java.sql.DriverManager.getConnection(DriverManager.java:297)
Since I am not getting this everytime, I am not able to guess that there is any connectivity issue. I can see lots of developers have the same problem, but for them it happens everytime. Please help me, since i am literally stuck in solving this problem.

I was having a similar problem, I tried using the IP address instead of the host name in the database URL, and it worked for me.
Example jdbc:
...(DESCRIPTION=(ADDRESS.....(HOST=1.1.1.1)..)

This is probably a network issue:
Is there a firewall that's giving you trouble? Try to telnet to the port. Is the firewall stateful?
Is the DNS too slow (use IP address instead of hostname, try DNS lookup)
Do you close the connections? Are you overloading the Listener?

I would have a closer look and perhaps set a break point in
at oracle.jdbc.ttc7.TTC7Protocol.handleIOException(TTC7Protocol.java:3678)
to see the precise IOException handled. This will tell you the underlying cause, which can help diagnose the problem.