By default, WireMock Cloud will serve a generic 404 page if an incoming HTTP request is not matched to any stub mapping. Often this is not a problem, but in some instances it is desirable to serve your own response. This can be achieved using the Priority parameter when creating stubs. By creating a stub which has loose (non-specific) matching criteria and a low priority setting, requests will “fall through” to this if they’re not matched to a more specific stub.Documentation Index
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Example
Suppose you want to serve a403 Unauthorized response with a meaningful response body when a request is not matched rather than the default 404. Additionally you
want to serve 200 response when a GET request is made to /examples/12.
Start by creating a stub with ANY as the method. Open the Advanced section and change the URL match type to Any URL.
Also in the Advanced section set the Priority to 10 (the lowest).

403 and the body content to "Sorry, you can't do that".

GET, the URL to /examples/12 and the response body to "Example 12 body" (keeping the Status as 200).
Now if you make a request that matches the specific stub you will see a response with a 200 status and the success message:
403 response.