ConnectionError: Failed to connect to localhost:undefined in 15000ms

Question

I am using KnexJs attempting to connect to a local Microsoft SQL Server Express. However, with the below configuration, I am getting an error. I've followed the typical steps, but I'm still getting the error.

What I've tried:

1. Set up a SQL Server authentication login for the database
2. Enable SQL Server authentication on the server
3. Enable TCP/IP on the server
4. Restart the Windows services
5. Restart the SQL Server through SQL Server Management Studio
6. Verify ability to log in through SQL Server Management Studio

Configuration / query code:

    let mssql = knex({
        client: 'mssql',
        connection: {
          host: 'localhost\\sqlexpress',
          user: 'test',
          password: 'test',
          database: 'AdventureWorks2017',
          // port:1433,
          // options: {
          //   trustedConnection: true
          // },
          useNullAsDefault: true
        }
      });

    mssql.raw('select 1 as result').then(function (result) {
      console.log('result');
      console.log(result);
      mainWindow.webContents.send('testConnectionResponse', result === 1);
      event.sender.send('testConnectionResponse', result === 1);
    }).catch(function (err) {
      console.log(err);
      mainWindow.webContents.send('query-error', err);
    }).finally(() => {
      mssql.destroy();
    });

Error:

ConnectionError: Failed to connect to localhost:undefined in 15000ms

Answer 1

It turns out that I also needed to enable the SQL Server Browser windows service like so:

1. Navigate to "Services"
2. Select "Properties" on "SQL Server Browser"
3. Flip "Start up type" to "Automatic"
4. Start the service

Success!