Some websites use separate URLs to serve desktop and smartphone users. A faulty redirect is when a desktop page redirects smartphone users to a page on the smartphone-optimized website that is not relevant to their query. A typical example is when all pages on the desktop site redirect smartphone users to the homepage of the smartphone-optimized site. For example, in the figure below, the redirects shown as red arrows are considered faulty:
This kind of redirect disrupts a user's workflow and may lead them to stop using the site and go elsewhere. Even if the user perseveres and finds the correct page on the smartphone-optimized site, irrelevant redirects add more work, which is particularly troublesome for users on slower mobile networks. In addition to frustrating users, these faulty redirects can cause problems with our crawling, indexing, and ranking algorithms.
If you get a “Faulty redirect” smartphone crawl error for URLs on your site, you can fix the problem by redirecting smartphone users from a desktop page to its equivalent smartphone-optimized page. If the content doesn't exist in a smartphone-friendly format, keeping users on the desktop content is better than redirecting to an irrelevant page.