P21 - External Pages Not Found

Alert Properties Alert Description
Alert Name External pages not found
Code P21
Description Unable to access external URLs referencing to other website pages on tags
Level Error

What is a 404 (Page Not Found) error?

If server requests for a web page reveal the absence of the page, it will return a 404 error response, called “Error 404”.

404 errors won’t impact your site’s search performance, and you can safely ignore them if you’re certain that the URLs should not exist on your site. It’s important to make sure that these and other invalid URLs return a proper 404 HTTP response code, and that they are not blocked by the site’s robots.txt file.

How to resolve the issue?

In case of external pages, indexed by search engines, make sure it does not have 404 errors.

In theory, 404s have an impact on rankings but not of the whole site. If a page returns a 404 error code, it means it doesn’t exist, so search engines will not index it. Just make sure your pages exist if you want them to rank since having thousands and thousands of 404 pages can impact your overall website.

The actual 404 pages do not hurt SEO directly, but the links that contain URLs pointing to those pages can wreak some damage for your site rankings.

Learn more about 404 errors here.
Learn about Soft 404 errors here.