Server Error in '/' Application.
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This type of page is not served.
Description: The type of page you have requested is not served because it has been explicitly forbidden. The extension '.mdb' may be incorrect. Please review the URL below and make sure that it is spelled correctly.

Requested Url: /directory/file_requested.mdb

SOLUTION DETAILS:
STOP IIS
Login to Server -> IIS -> Websites
Right click on the web application -> properties
Home Directory -> Configuration
Scroll down the 'ISAPI' extensions -> select '.mdb' -> Remove.
iisreset