Could not open a connection to SQL Server

1. Why can't I connect to SQL Server?
2. Could not open a connection to the SQL Server error 40?
3. Why is my SQL Server not opening?
4. Could not open a connection to SQL Server 1326?

Why can't I connect to SQL Server?

The following common scenarios can cause connectivity problems: Incorrect IP address for the Server field. Make sure that the IP address matches the entry in the SQL Server error log file. Incorrect server name in the Server field.

Could not open a connection to the SQL Server error 40?

Make sure that TCP/IP is enabled.

To make it enable follow the steps: Click on Configuration Manager of SQL Server. Now you can check the TCP/IP port status as Enabled or Disabled. You need to make it Enable and click on status to change port Properties. Now fill Default Port no 1433 click on OK button.

Why is my SQL Server not opening?

You may not have enough disk space available. Free additional disk space by deleting other files on the temp db drive and then restart SQL Server. Check for additional errors in the event log that may indicate why the temp db files could not be initialized.

Could not open a connection to SQL Server 1326?

Error 1326 means "Logon failure: unknown user name or bad password." This error is raised because the IIS Service does not have any rights to use the named pipe. In order for a client to gain access to a Windows NT named pipe, the client needs to be validated by the Windows NT server.