Exception Occurred - ResponseFactory::controller()

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I've got this exception happening on a 8.5.4 production site:

Exception Occurred: /concrete/src/Http/ResponseFactory.php:160 Argument 1 passed to Concrete\Core\Http\ResponseFactory::controller() must be an instance of Concrete\Core\Controller\Controller, null given, called in /concrete/src/Http/ResponseFactory.php on line 367

The site appears to be running smoothly. No errors are appearing on the server logs, and I can't replicate it in a Dev environment. The site has fairly small traffic - probably about 500 unique visits a day, and I get this exception happening sporadically probably about 10-12 times a day.

I am not quite sure where is best to start looking - Can anyone offer advice about what ResponseFactory does please?

drbiskit
 
rajeshsundaram replied on at Permalink Reply
Changing the "Page Type" from "None" => "Page" fixes this issue for me