I recently put a new asp.net website up into production and set the IIS asp.net service from 2.0 (default) to 4.0 and restarted the WWW service. Now however the website does not seem to read aspx files, when attempting to load Default.aspx, i get 404 file not found error - however loading some .html or .txt files will display the file correctly. The script maps is correctly generated i.e. i do see .aspx under the script maps pointing to the correct isapi.dll under 4.0 framework. What could possibly be the issue?

migrated from stackoverflow.com Jul 12 '11 at 17:24

This question came from our site for professional and enthusiast programmers.

  • 1
    Is the App Pool for the website correctly defined and running? – Dave Jul 12 '11 at 13:50
  • 1
    Have you tried other .aspx files (ie, is default.aspx (home page) the only issue?). – Gregory A Beamer Jul 12 '11 at 13:53

If you are seeing this behavior for all .aspx pages, are you sure you have ASP.NET 4.0 installed? You could try running aspnet_regiis.exe -i from the install directory of the 4.0 framework.

On Windows7 64 bit the default install location is:

and for 32 bit it should be:


Click on the documents icon in IIS and add the home page name.


Usually, I use Failed Request Tracing, together with Process Monitor to hunt these kind of issues.

With these tools, you can monitor the request as it runs through IIS as well as seeing whether your physical file actually gets requested or not (I had similar issues before where 404 simply meens "Not allowed to get these type of files").


hi use separate pool for all deployed site if you are use IIS 6, because 4.0 must use with separate pool.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy