Oracle Error Message
 TNS-12170: TNS:Connect timeout occurred
Reason for the Error
Oracle Error TNS-12170: TNS:Connect timeout occurred is a common error that can occur when trying to connect to an Oracle database. This error indicates that the client was unable to establish a connection with the server due to a timeout.
There are several reasons why this error may occur:
- Network connectivity issues: The most common reason for this error is network connectivity issues. If there is a problem with the network connection between the client and server, the client may not be able to establish a connection with the server.
- Firewall settings: Firewall settings can also cause this error. If the firewall is blocking the connection between the client and server, the client may not be able to establish a connection with the server.
- Incorrect configuration: This error can also occur due to incorrect configuration of the client or server. For example, if the client is using an incorrect port number or IP address to connect to the server, the connection may not be established.
- Database server issues: This error can also occur if there are issues with the database server itself. For example, if the database server is down or experiencing performance issues, the client may not be able to establish a connection with the server.
Solution
To fix this error, there are several steps you can take:
- Check network connectivity: The first step is to check the network connectivity between the client and server. Make sure that there are no network connectivity issues that may be causing the problem.
- Check firewall settings: If there are no network connectivity issues, check the firewall settings to make sure that the connection is not being blocked.
- Check configuration settings: Check the configuration settings for both the client and server to ensure that they are correct. Verify that the client is using the correct port number and IP address to connect to the server.
- Restart the database server: If the above steps do not resolve the issue, try restarting the database server. This can often resolve any issues that may be causing the problem.
- Increase the connection timeout value: If the connection timeout value is too low, it can cause this error. Try increasing the connection timeout value to see if that resolves the issue.
Change one or more of the parameters SQLNET.INBOUND CONNECT TIMEOUT, SQLNET.SEND TIMEOUT, and SQLNET.RECV TIMEOUT in sqlnet.ora to bigger values if the problem was caused by a slow network or system.
Use the address in sqlnet.log to locate the source and limit access if a malicious client is suspected.
Recall that logged addresses could not be trustworthy since they might be faked (for example, in TCP/IP).
