In general, 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.
Here's how you should handle 404 errors:
- Decide if it's worth fixing. Many (most?) 404 errors are not worth fixing because 404s don't harm your site's indexing or ranking.
- If it is a submitted URL (an error), it is worth fixing.
- If it is a deleted page that has no replacement or equivalent, returning a 404 is the right thing to do. The report should stop showing the 404 after about a month.
- If it is a bad URL generated by a script, or that never have existed on your site, you probably don't need to worry about it. It might bother you to see it on your report, but you don't need to fix it, unless the URL is a commonly misspelled link (see below). 404 errors should be dropped from the report after about a month.
- If the URL was submitted for indexing, (the status is Error),
- Inspect the URL to see where it was submitted from by clicking the submit icon next to the URL and look at the Discovery information. Update the sitemap as necessary.
- If the content has moved, add a redirect.
- If you have permanently deleted content without intending to replace it with newer, related content, let the old URL return a 404 or 410. Currently Google treats 410s (Gone) the same as 404s (Not found). Returning a code other than 404 or 410 for a non-existent page (or redirecting users to another page, such as the homepage, instead of returning a 404) can be problematic. Such pages are called soft 404s, and can be confusing to both users and search engines.
- If the URL is unknown: You might occasionally see 404 errors for URLs that never existed on your site. These errors can occur when someone browses to a non-existent URL on your site - perhaps someone mistyped a URL in the browser, or someone mistyped a link URL. If it's a very common error, you might create a redirect for it.
<a href="helloworld.pdf" onClick="_gaq.push(['_trackPageview','/download-helloworld']);"> Hello World PDF</a>
When Googlebot sees this code, it might try to crawl the URL
http://www.example.com/download-helloworld, even though it's not a real page. In this case, the link may appear as a 404 (Not Found) error in the Crawl Errors report. Google is working to prevent this type of crawl error. This error has no effect on the crawling or ranking of your site.
- Don't create fake content, redirect to your homepage, or use robots.txt to block 404s—all of these things make it harder for us to recognize your site’s structure and process it properly. We call these soft 404 errors.(Once Google has successfully crawled a URL, it can try to crawl that URL forever. Issuing a 300-level redirect will delay the recrawl attempt, possibly for a very long time.) Submitting a URL removal request using the URL removal tool will not remove the error from this report.