The Network Adapter Could Not Establish The Connection Error

Welcome Readers, While trying to make a new connection in SQL Developer or if you are logging into the database by using the SQL *Plus editor if you have encountered a TNS IO error that says “The Network Adapter could not establish the connection error” then you don’t need to worry, you are at the right place.

Here in this article, I am going to share the information through which you will be able to fix this error successfully. So now, let’s take a look below to know more about the fixes regarding this badass TNS error.

The Network Adapter Could Not Establish The Connection

Before going to fix The Network Adapter Could Not Establish The Connection Error, first, you should have to know that Oracle SQL is an integrated development environment that was created to work with SQL on Oracle databases. This product is developed and provided by the Oracle Corporation and to use the services of this product, you do not need to pay any cost.

It is based on the Java Development Kit. Recently, there have been several user reports about an “IO Error: The Network Adapter Could Not Establish The Connection” Error when they are testing a database connection. If you are one of them who get this error, then don’t need to worry. Below in this article, I am going to share the fixes, and to read and following them, you will be able to fix this error successfully. So now, let’s take a look below to know more about the fixes.

What are the Causes of the “The Network Adapter Could Not Establish The Connection” Error?

With this section, you will be able to know about the causes for the “The Network Adapter Could Not Establish The Connection” Error. So, before going to fix this error, first, you should have to know about the causes behind this error. So now, let’s take a look below to know more about them.

Incorrect Details: First, you should have to ensure that the connection details are entered correctly or not. In order to establish the connection, first, you should have to be entered correctly the Hostname, Port, Username, and password. If any of the above-mentioned values are not entered properly, then the error may occur.
Disabled Service: It will be very important for you that the listener service is started in the background for the application to work properly, if it is not started or it is disabled, then the error maybe occur.

Now, you are aware of the causes for the “The Network Adapter Could Not Establish The Connection” Error. So now, to fix this error, simply read and follow the below-given solutions.

How to Fix the Network Adapter Could Not Establish The Connection Error?

Here in this section, I am going to share all the possible solutions regarding the “The Network Adapter Could Not Establish The Connection” Error, and to read and follow this whole section carefully, you will be able to fix this error successfully. So now, let’s take a look below to know more about the solutions.

Solution 1: Check Your Entered Details

First, you have to recheck your entered details and you have to ensure that the details that you have entered for the connection are correct. Sometimes, it happens that your entered details do not match the server configurations and due to this the error occurs. Therefore, below in this section, I am going to share the steps through which you will be able to check and enter the details again. So now, let’s take a look below to know more about the steps.

First, you have to download and install Notepad++.
Then you have to navigate to the following address:

DB Home: C:/app/Username/product/11.2.0(version might differ)/dbhome_1/Network/Admin

After that, you have to right-click on the “tnsnames.ora” file and then you have to select the “Open With Norepad++” option.
Now, under the “ORCL=” heading, you have to note the “Port” and the “Host” details.
Also, you have to note the “Service Name”.
Then while establishing the network connection, you have to enter these details and then simply click on “Test”.
And lastly, you have to check for the issue is solved or not.

Solution 2: Start the Listener Service

If you are getting this error, then it may be possible that the listener service has not been started. In order to establish the connection, this service is required by the application. So now, if you want to start the listener service, then simply read and follow this whole section. With this section, you will be able to do it successfully. So now, let’s take a look below to know more about the steps.

First, you have to press the “Windows” + “R” keys altogether and open the Run prompt.
Then in the Run box, you have to type in “cmd” and then you have to press “Shift” + “Ctrl” + “Enter” keys altogether to provide the administrative privileges.
Then you have to type in the command “lsnrctl status” to check if the service is started or not.
If you get the result that is similar to the image below, then it means that the listener service has not been started.
Then you have to enter the command “lsnrctl start” to start the service manually.
After that the listener service has been started, then you have to open the application and then check out to see if a new connection can be established.

SQL Developer FAQs

Here in this section, I am going to share some frequently asked questions with answers. So now, let’s take a look below to know more about them.

Q.1. How can I start SQL Developer?

Ans. SQL Developer serves its services as a graphical user interface (GUI) which is designed and developed by Oracle. This is one of the simplest database management tools and to access its services, you don’t need to install it. You just have to download it and use it.

Just make a click on the sqldeveloper.exe, and you can start SQL Developer. This file is located in the software’s root directory.

Q.2.What is SID in the SQL Developer?

Ans. SID stands for the System Identifier or Site Identifier. For your Database, it is a unique name. While talking about the Oracle ecosystem, then you will find that every database is given a unique name. And with the help of this unique name, we will be able to connect with a specific database.

You will be able to find out the SID of your Database by querying the v$thread view. For Example SELECT instance FROM v$thread;

Q.3. How to Download the SQL Developer?

Ans. Before going to download the SQL Developer, first, you should have to know that the SQL Developer is totally a free database management tool provided by Oracle. To download it, you have to make your visit to oracle.com. Once you will be on the download page of the website oracle.com, then there you can find this tool under the Developer Tools category.

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Final Words

I hope so, all the information that I have shared above in this article will be beneficial for you. Above in this article, I have shared all the possible solutions through which you will be able to fix The Network Adapter Could Not Establish The Connection Error successfully.

So now, if you feel better with all the information that I have shared above in this article, or still, if you have any queries or any suggestions regarding this article, then drop your comment below in the given comment section, and you will be able to share your experience with us.

The Network Adapter Could Not Establish The Connection Error – Fix