Solutions that are not available for IIS server applications

The first may be because IIS installed after the. NET Framework first causes. NET to not be registered in IIS:

Run the Aspnet_regiis-u uninstall from the. NET command-line tool and aspnet_regiis-i the installation
Then restart IIS, remove the default application, and then recreate the site as an application.

The second (probably because of insufficient permissions):

The ASPNET account does not have permissions for the server directory specified by IIS. Find tools-Folder Options-view-Using simple folder sharing (recommended) In Explorer remove the front tick and then right-click on the server's designated directory, attribute-security-add-advanced-Find Now, add the ASPNET account and give it a full access permission. If you do this, you will find that you have not made that mistake, but if you access the database you may be prompted that the ASPNET account does not have permission to access the database. This hint is much clearer, put the account in the database to add the appropriate permissions on it.

Third: (possibly because of application pool configuration issues)

To create a new application pool, the steps:
1. Click Start, point to Programs, and then click Control Panel.
2. Double-click Administrative Tools, and then double-click inte.net Information Services (IIS).
3. Right-click application Pool, point to New, and then click Application Pool.
4. Type AppPool1 in the application pool ID text box.
5. Click OK.
To assign an application to an application pool:
1. Click Start, point to Programs, and then click Control Panel.
2. Double-click Administrative Tools, and then double-click inte.net Information Services (IIS).
3. Double-click Web site.
4. Double-click Default Web site.
5. Right-click DebugApp1, and then click Properties.

6. In the Home Directory tab, in the Application Pool list box, select AppPool1, and then click OK.

Fourth (because the ASP.net state service is not started):

In the services, locate ASP. NET status service to see if it is not started, if it is not started, you need to double-click it, and then choose Start.

Run the *.aspx file in IIS again to see if it's normal.

This is the fourth kind of I have tried the first three solutions, the problem is still unresolved, helpless, to find their own solutions, think of a service may be stopped may also lead to the emergence of this error, so after the test, and finally resolved.