Users will occasionally come to a page that doesn't exist on your site, either by following a broken link or typing in the wrong URL. Having a custom 404 page30 that kindly guides users back to a working page on your site can greatly improve a user's experience. Your 404 page should probably have a link back to your root page and could also provide links to popular or related content on your site. You can use Google Search Console to find the sources of URLs causing "not found" errors31.
QUOTE: “Fixing the problem depends on the issue you have. For example, if it’s a pop-up, you’ll need to remove all the pop-up ads from your site. But if the issue is high ad density on a page, you’ll need to reduce the number of ads. Once you fix the issues, you can submit your site for a re-review. We’ll look at a new sample of pages and may find ad experiences that were missed previously. We’ll email you when the results are in.” Google, 2017
Advertising with Google won't have any effect on your site's presence in our search results. Google never accepts money to include or rank sites in our search results, and it costs nothing to appear in our organic search results. Free resources such as Search Console, the official Webmaster Central blog, and our discussion forum can provide you with a great deal of information about how to optimize your site for organic search.