Problem Description:

Could not load file or assembly 'System.Data.SQLite' or one of its dependencies. An attempt was made to load a program with an incorrect format.

Likely to be reproduced when:

You will usually encounter this problem when you have downloaded a sample application that is a 32-bit application targeted for ASP.NET 2.0 or 3.5, and you have IIS7 on a 64-bit OS running .NET 4.0, because the default setting for running 32-bit application on IIS7 with 64-bit OS is false.

Resolution:

1. Go to IIS Management Console
Start -> Administration Tools -> Internet Information Services (IIS) Manager

2. Expand your server in the left pane and go to Application Pools

3. Right click to select ‘Add Application Pool’ 

4. Create anew AppPool. I have named it ASP.NET v2.0 AppPool (32-bit) and selected .NET Framework v2.0.50727 because I intend to run my ASP.NET 3.5 application on it.

5. Now right click the newly created AppPool and select Advanced Settings

6. Change the property “Enable 32-Bit Applications” from False to True 

7. Now select your actual web application from the left panel. Right click the web application, and go to Manage Application -> Advanced Settings 

8. Change the Property “Application Pool” to your newly created AppPool. 

And… the error is gone…