What happens when you have dozens and dozens of JavaScript and CSS includes, some hosting internally and some hosted externally? Well, sometimes it is just too much for Google’s testing tools to handle and they just give up waiting on a response from the includes.

A recent case posted in the Google Webmaster Help forums shows one site that has 86 JavaScript includes and 21 CSS file includes and Google just is being impatient with it and returning errors in their testing tools, but in the Fetch tool and the mobile friendly testing tool.

Here is a screen shot of the mobile testing tool:

Google’s John Mueller replied to the webmaster explaining this saying:

So keep it simple with all the includes.

Forum discussion at Google Webmaster Help.