HTTP Error 500.19 - Internal Server Error The requested page cannot be accessed because the related configuration data for the page is invalid
The application pool of the website does not have sufficient privilliage for
accessing the folder of the website
On Run type inetmgr to open IIS.
Select your website from the Sites panel.
For that site, click Edit Permission link from right Action panel.
Now a new property window will be opened.
Select Security Tab from the Property Window.
Select the user from Group or user names.
Now click the Edit button for the selected User.
If any of the listed deny checkboxes are checked then remove them
as per your required permission level.
This will difinitely resolve your problem.