Parser Error: Unknown server tag ‘asp:ScriptManager’

Problem

You see this message when attempting to run your application:

Server Error in ‘XXX’ Application.

Parser Error

Description:  An error occurred during the parsing of a resource required to service this request.  Please review the following specific parse error details and modify your source file appropriately.

Parser Error Message:  Unknown server tag ‘asp:ScriptManager’.

This error occurs when you overwrite your application’s Web.config file with an older version that does not contain the appropriate information to enable Ajax functionality in your application.

Solution

Step 1:  Make a copy of your application’s Web.config file.

Step 2:  Generate a new application using Iron Speed Designer V4.2 or later.  This will generate a good Web.config file.

Step 3:  Copy the Web.config file from the new application folder into your application folder, overwriting the older or mis-configured Web.config file.

Step 4:  Apply any necessary changes to the new Web.config file that may be present in your older Web.config file (from the backup copy).

See Also

Part VII:  Troubleshooting Applications

Application Won’t Run

Application Runs But No Data is Displayed

Application Error Messages