If you have received this warning, don’t be alarmed. You are not being hit with a penalty; rather, you are simply being informed that Google can no longer see your entire website, and that this could result in a lower search ranking.
The Simple Fix
To fix this error, there is a simply trick that you can implement. In your robots.txt file, simply add the following lines:
Doing so will allow the Googlebot to see your entire website, and will keep your search rankings from being impacted. It is also important to keep in mind that when performing this search, Google tends to not delve too deeply into your website. They will simply look at the homepage, and the mobile view of a website. So be sure that you are changing the homepage for not only the desktop version of your site, but for the mobile version as well.
If you are still receiving this error after performing the above trick, you may need to do a bit of diagnosing. First, look into the CMS you are using (if any) and see if they block Googlebot. For example, many WordPress sites received this warning message because the /wp-includes/ folder was blocked. Talk to your CMS provider and see if they have any solutions to your problem. You can also use Google’s Render and Fetch tools to see if your problems have been fixed.
Hopefully this little trick will help get your website back on track, and your search rankings were not impacted in the meantime.