Error:This page allows a limit of 200 controls, and that limit has been exceeded

I received the above error when extending an existing web application in SharePoint 2010.

Solution :
SharePoint be default limits the number of controls per page to 200 in the extended site web.config file, all what you have to do is:

1. Edit the web.config of your application (e.g: C:\Inetpub\wwwroot\wss\VirtualDirectories\80)
2. Search for configuration/SharePoint/SafeMode then change the MaxControls attribute to a suitable value higher than 200, I tried 500 it worked like charm.