This check determines whether the web.config file for the identified web application contains an unsupported configuration.
When batch compilation is enabled, ASP.NET will batch compile all pages in the virtual directory. SharePoint supports batch compilation of pages within the _layouts folder; however it does not support the batch compilation of pages in SharePoint document libraries.
Verify that the batch mode is disabled in the web.config file for the web application. To do so, open the Internet Information Services Manager, open the server branch in the tree view on the left side and then open Sites branch. Find the affected web application, right-click its name in the tree view and click Explore. Open web.config file with Notepad and make sure that following is configured:
<compilation batch="false" debug="false">
Additional information can be found in the following articles: