Most likely causes: The directory or file specified does not exist on the Web server. The URL contains a typographical error. A custom filter or module, such as URLScan, restricts access to the file.
Things you can try: Create the content on the Web server. Review the browser URL. Check the failed request tracing log and see which module is calling SetStatus. For more information, click here.
Detailed Error Information:
Requested URL http://localhost:2409/checkout Physical Path C:\Users\Developer\Documents\Virto Commerce 1.8\Projects\SampleProject\checkout Logon Method Anonymous Logon User Anonymous Request Tracing Directory C:\Users\Developer\Documents\IISExpress\TraceLogFiles\VIRTOCOMMERCE-SAMPLEPROJECT
More Information: This error means that the file or directory does not exist on the server. Create the file or directory and try the request again.
Instead using "Checkout" from the Top Menu or the Button "Continue to Checkout" within the Cart Overview at the top are working as expected.
This is a known issue and has been fixed already in the latest code. You can get the latest code from github master branch, which contains the fix or update RouteConfig.cs file manually (it is in the frontend project).
Hope this helps,