BMoney in case you're not aware, there are two different error messages involved here:
- If you access the link directly, you get an HTTP response with " The page you requested could not be found. " and a link to the homepage
- If you click that link inside your Flarum, you'll see a red box appear at the bottom of the screen with the text "The requested resource was not found."
You should be able to customize those strings with the Flagrow Linguist extension, just search for them and replace them with something else. Keep in mind those messages are shown anytime a page/resource does not exist, including non existing pages, user profiles, and many other.
If you only want to customize the HTTP response, you can use Flagrow Custom HTML Error to return the HTML of your choosing for the error page.
EDIT: and of course if you're familiar with extension development, you should be able to provide special error messages for only those specific actions via an extension.
