SharePoint Access Denied to Root Site of Web Application
Log into the SharePoint 2013 Central Administration site.
Open Application Management.
Open Manage web applications.
Select the web application that has the problem and open Authentication Providers from the ribbon bar.
Open the authentication provider zone that you are using (it is probably just Default).
Check the Enable anonymous access option and then Save the Authentication settings. It can take a minute or two to save the settings, so after you click Save just wait for the Authentication Setting window to close.
After the Authentication Setting window closes and you can see the Authentication Providers window again then try to access your root site again and now you should be able to get to the home page without any Access Denied errors.
Now we don't want to leave anonymous access enabled so once again open the authentication provider zone that you are using and now uncheck Enable anonymous access and then Save the Authentication settings.
You should now still be able to access the root site of your web application and the issue has been fixed.
Log into the SharePoint 2013 Central Administration site.
Open Application Management.
Open Manage web applications.
Select the web application that has the problem and open Authentication Providers from the ribbon bar.
Open the authentication provider zone that you are using (it is probably just Default).
Check the Enable anonymous access option and then Save the Authentication settings. It can take a minute or two to save the settings, so after you click Save just wait for the Authentication Setting window to close.
After the Authentication Setting window closes and you can see the Authentication Providers window again then try to access your root site again and now you should be able to get to the home page without any Access Denied errors.
Now we don't want to leave anonymous access enabled so once again open the authentication provider zone that you are using and now uncheck Enable anonymous access and then Save the Authentication settings.
You should now still be able to access the root site of your web application and the issue has been fixed.
