Searchers often struggle to get information they are seeking simply because some smartphone-optimized websites are misconfigured. Many users who rely on smartphones for information regularly receive an error page or are redirected to an inappropriate page; but this is different to desktop users who get all the information they require.

Googlebot identifies problems such as these and regard them as crawl errors; they drastically disrupt a website’s user experience and are the basis of some of Google’s ranking changes for smartphone search results. Fortunately Google now has an expanded version of Crawl Errors that feature in Webmaster Tools thereby assisting to identify pages on a user’s site and show these types of problems. Google introduced a new smartphone errors tab where users share pages they’ve identified with errors only found with Googlebot for smartphones.

Some of the errors identified by Google are as follows:

Server errors: this whereby Googlebot receives an HTTP error status code when it crawled the page.

Not found errors and soft 404s: Some pages reflect a “not found” message on Googleboot, this can be either by returning an HTTP 404 status code or when the page is detected as a soft error page.

Faulty redirects: this is a smartphone precise fault that happens when a desktop page redirects smartphone users to a page that is not relevant to their query. A good example that can be used is when all pages on the desktop site redirect smartphone users to the homepage of the smartphone-optimised site.

Blocked URLs: this is a situation whereby a site’s robots.txt clearly prohibit crawling by Googlebot for smartphones. Smartphone specific robots.txt regularly disallow directives; as such, users should check their server configuration and should report to Webmaster Tools if they discover any blocked URLs.

Rectifying issues that you see in Webmaster Tools can improve the efficiency of your site let alone assist Google’s algorithms to improve the index of your content.

Source: http://googlewebmastercentral.blogspot.com/2013/12smartphone-crawl-errors-in-webmaster.html