If the server or application fileEncoding attribute setting is configured to use UTF-16 and UTF-16 is not the encoding that is used for an .aspx page in the scope of the configuration file, the output that is sent to the client browser will be corrupted and might possibly display the source code of the page. Make sure that the configured fileEncoding value matches the encoding that is being used in the page.
Default Configuration
The following default globalization element is not explicitly configured in the Machine.config file or in the root Web.config file. However, it is the default configuration that is returned by application.
<globalization requestEncoding="utf-8"
responseEncoding="utf-8"
fileEncoding=""
culture=""
uiCulture=""
enableClientBasedCulture="false"
responseHeaderEncoding="utf-8"
resourceProviderFactoryType=""
enableBestFitResponseEncoding="false" />