"Sys" is undefined

I have migrated my application to .Net Framework 4.5. I am not using any update panel and not even script manager.

One of the page which is throwing this error has the below code:

<bod><form>

<script>

       Sys.Application.add_load(SectionMethod)

</script>

This was working fine before migration.

I used fiddler and found that ScriptResources.axd?,,,,,,,, file is not able to locate at server. But its working fine in my machine and at other server.