The 'X is undefined' error occurs or controls are rendered with incorrect styles

• Oct 06, 2023
• 2 minutes to read

Possible Errors

• “‘aspx***’ is undefined”

• “ASPxClient*** is undefined”

• The default styles/images/scripts for DevExpress ASP.NET controls are not loaded.

Solution

Check the following to solve this issue:

1. Make sure the ASPxHttpHandlerModule is registered in Web.config.

2. Make sure the application’s folder is marked as a separate IIS application.

3. Add “ Full control “ permission for the “ IIS_IUSRS “ account in the application folder.

4. Rewrite URL. Add an exception for the DXR.axd URL if you specify a Rewrite URL rule in your Proxy Layer/URL Rewrite Module that blocks/rewrites requests from resource handlers:

See Also

• How To: resolve the “Cannot add duplicate collection entry of type ‘add’ with unique key attribute ‘name’ set to ‘ASPxHttpHandlerModule’” error