No process is on the other end of the pipe (SQL Server 2012)

I've got this error:

A connection was successfully established with the server, but then an error occurred
during the login process. (provider: Shared Memory Provider, error: 0 - No process is
on the other end of the pipe.)

(Microsoft SQL Server, Error: 233)

I know, there are similar questions on this site, and the answer is, to enable TCP/IP and pipes. But I enabled both, and still doesn't work:

I am using Microsoft SQL Server 2012 and the user has full permissions.

Solution 1:

The server was set to Windows Authentication only by default. There isn't any notification, that the origin of the errors is that, so it's hard to figure it out. The SQL Management studio does not warn you, even if you create a user with SQL Authentication only.

So the answer is: Switch from Windows to SQL Authentication:

1. Right click on the server name and select properties;
2. Select security tab;
3. Enable the SQL Server and Windows Authentication mode;
4. Restart the SQL Server service.

You can now connect with your login/password.

Here are the directions by Microsoft: https://docs.microsoft.com/en-us/sql/database-engine/configure-windows/change-server-authentication-mode?view=sql-server-ver15

Solution 2:

To solve this, connect to SQL Management Studio using Windows Authentication, then right-click on server node Properties->Security and enable SQL Server and Windows Authentication mode. If you're using 'sa' make sure the account is enabled. To do this open 'sa' under Logins and view Status.

If this didn't work, you may need to reinstall SQL Server