Error Messages

Error messages are usually displayed due to configuration errors in WebMap or issues with GeognoSIS instances.

WebMap allows you to customise error dialog boxes for a friendlier user experience. The installer includes two generic error pages:



Note: See What is Installed (Folder Structure) for the location of these editable files.

Specific error pages can be used for specific HTML status codes. 

To do this, edit the customError section (found in web.config file). All you have to do is add another error node:




Default page used if the site fails to load. Initially set to genericerror.aspx


Sets when the error messages are displayed.

  • ON - Always show error messages
  • OFF - Never show error messages
  • RemoteOnly - Only show messages on the host machine when localhost is used.


HTML error code. Allows specific error pages to be displayed when specific error codes are returned.


File redirected to when error code is returned. This overrides the default error page.

Editing the web.config

<customErrors defaultRedirect="genericerror.aspx" mode="RemoteOnly">
<error statusCode="404" redirect="NotFound.aspx"/>

HTTP Error 404.15

This error occurs if the query string in a Get Feature Information request is too long.

When selecting a point on the map, Cadcorp SIS WebMap creates a query string that is handled by an IIS server (the length of this query string is dependent on a number of factors such as the number of overlays and length of the overlay names).

  1. To resolve this error, open IIS > find your application in the tree > Request filtering > Edit Feature Settings.
  2. Increase “Maximum query string (Bytes)” as appropriate.

Appropriate string length is extremely subjective and dependent on the data being used.

Use the developer tools feature within your browser to check the length; now set the new length to exceed this. If you use the OGC CGI EXE in a separate IIS application, increase the request limit here and not on WebMap.

The request filtering module is a built-in security feature of IIS and care should be taken when adjusting these settings. Click here for more information on request filtering.