You will get this error in the step by step tutorial (on page here) provided by Microsoft that starts from here.
If you look in your solution you will find 'SQL Server CE' database is being used and to which the application was somehow unable to connect and thus this message comes up.
Once you update the connectionString to use a regular 'SQL Server' database will fix this titled issue.
How to fix?
In Part 4 of this step by step turorial, you probably have added following code in you connectionString:
Now, delete above chunk of codes and run the application and try to navigate to ‘Store’ controller, this will automatically create the new and regular ‘SQL Server’ Database for your project and will also seed some dummy data from a file ‘SampleData.cs’, you will find this in ‘Model’ folder.
And now, you are ready to go further in that step by step tutorial.
I hope this fix will help you. Thanks.