How can you configure routes for such a structure.

As InsiteFX said, make sure your Modules are setup like he showed previously (with each module being listed). Then create a new routes file at Modules\Blog\Config\Routes.php. Those routes should be automatically read by the default configuration.

To answer the original question - the problem you're running into is the difference in capitalization with the uri having a lowercase blog and the namespace being ucfirst Blog so it's not finding the class.

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