500 Error from web.config

Question

User1510859543 posted

I have 2 web apps on the same server but one is giving a 500 Error and I have got it down to a problem with the web.config file.  I added the markup below in the web.config file after the <system.web> section.  It was added to handle large jquery ajax uploads and cannot figure why the one app fails and the other works fine even though both have the same web.config.  Any ideas where I can look or do to resolve this issue as the 500 error gives no detail.

  <!--
    Added system.web.extensions to handle jquery ajax calls to handle large images
    e.g. in CustEstimate.aspx
  -->
  <system.web.extensions>
    <scripting>
      <webServices>
        <jsonSerialization maxJsonLength="819200000" />
      </webServices>
    </scripting>
  </system.web.extensions>