The alerts are coming in the form of a message from within the Google Search Console (formerly Google Webmaster Tools), as well as a detailed email message like the one shown below.
The warning about suboptimal rankings is not new, but the Search Console notifications are.
Google updated their webmaster guidelines in October 2014 and warned then that blocking CSS and JS can result in “suboptimal rankings.” Now Google is making that message loud and clear by using notifications via email and the Search Console.
Why should you care?
If you received this notification, follow the instructions in the email to diagnose the issue and use the fetch and render tool within the Search Console to see what Google sees and identify resources your robots.txt file directives are blocking. In many cases this is being caused by website content management systems (CMS) by default blocking include folders which contain CSS and JS files.
As a follow-up, Google is also recommending that you add the following to your robots.txt file:
User-Agent: Googlebot Allow: .js Allow: .css
You should also double check to be sure you’re not missing anything by checking out the Blocked Resources section within the Google Search Console.
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Mark is a Partner and Senior Consultant at SureFire which he founded back in 2002. Prior to establishing SureFire he worked for KPMG Consulting. Today Mark heads up SEO, embracing the challenges that can come with complex website implementations. Outside of work, his interests beyond his family are running, snowsports, diving and fishing (badly).