When trying to access the storefront in a browser, an "AppConfig Table is NULL!!" error is thrown. This is often preceeded/followed by other errors indicating that the site cannot connect to the database. 

This is caused by the site failing to connect to the SQL DB during the initial application startup. 

The following steps should help you isolate the cause of the issue: 

1 - Verify that the DBConn string in the web.config file has been populated with a valid server name (and instance if applicable), database name, user name, and password. 

2 - Ensure that you have run the installation and/or upgrade scripts against your database, and that they completed without any significant errors. 

3 - If you are using integrated authentication, you MUST add the Windows NT user that ASP.NET is using to run the application to your SQL Server, and assign the user DB Owner permissions to the AspDotNetStorefront database. This is typically your web server’s NETWORK SERVICE account. 

4 - If you are unable to connect using integrated authentication or a custom DB user, try enabling SQL Server Authentication and attempt to run the site as the SA user. 

Note: It is not recommended to run a live site as SA for security reasons. This should only be done for the purpose of isolating connectivity issues with your site. If you need assistance configuring SQL Security please contact a DBA or qualified IT Professional. 

5 - Ensure that your SQL server has been configured to listen on named pipes and/or TCP/IP. Note that when using TCP/IP you must go into the advanced TCP/IP settings in SQL Configuration manager and enable each individual IP Address your wish your server to listen on. 

If you are unsure what your SQL Server name and instance name are, open SQL Management Studio 2005 (any version including Express) and look at the initial connection prompt. You wills see the server listed as something like MYCOMPUTER\SQLEXPRESS. This is the exact value you would enter in your web.config file as the Data Source. If you are using a hosted site, this value may also contain an IP address or fully qualified domain name such as 192.168.1.37 or sql15.myhostingcompany.com.