hexadecimal value 0x00 is an invalid character, web site crashed when upgraded to .NET 3.5

Problem

When we upgraded to Microsotf .NET Framework 3.5, some web sites crashed. Here are error messages.

     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: '.', hexadecimal value 0x00, is an invalid character. Line 2, position 1.

Source Error:

Line 1: <?xml version="1.0" encoding="utf-8"?>
Line 2: <xs:schema id="DataSetAdmin"
Line 3: <xs:annotation>
Line 4: <xs:appinfo source="urn:schemas-microsoft-com:xml-msdatasource">

Version Information: Microsoft .NET Framework Version:2.0.50727.1433; ASP.NET Version:2.0.50727.1433

Solution

Remove encoding attribute from your xml document.

From
<?xml version="1.0" encoding="utf-8"?>
To
<?xml version="1.0"?>

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