Skip to main content
BuyLog In
ASP.NET Web Forms Controls
Search in…
Docs > Troubleshooting > Client-Side Issues > The 'X is undefined' error occurs or controls are rendered with incorrect styles
All docs
V24.2
ASP.NET Web Forms Controls
.NET Support and Migration
Prerequisites
Supported Browsers
What's Installed
Get Started
Upgrade to a New Version
Common Concepts
Components
Security Considerations
Redistribution and Deployment
Troubleshooting
Get Started
Common Issues
Client-Side Issues
The 'X is undefined' error occurs or controls are rendered with incorrect styles
Cannot access DevExpress ASP.NET controls on the client
ReferenceError: 'X' is not defined
Microsoft JScript runtime error: 'X' is undefined
Server-Side Issues
Installation and Update Issues
Performance Issues
Grid-Related Issues
Themes-Related Issues
Get More Help
.NET Framework API Reference
Client API Reference
Download CHM

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

  • 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.

    The ASPxHttpHandlerModule allows DevExpress ASP.NET controls to load their resources. The Web.config file should contain a reference to this module in the system.web/httpModules and system.webServer/modules (for IIS7 in integrated mode) sections. Registration is automatic if you place a DevExpress control on a form in Design view or if you use Project Templates to create an application. You can register the module if you create controls at runtime.

    IIS (classic mode)

    <system.web>  
    <httpHandlers>  
    <add type="DevExpress.Web.ASPxHttpHandlerModule, DevExpress.Web.vX.Y, Version=X.Y.Z.0, Culture=neutral, PublicKeyToken=b88d1754d700e49a" verb="GET"  
    path="DX.ashx" validate="false" />  
    </httpHandlers>  
    <httpModules>  
    <add type="DevExpress.Web.ASPxHttpHandlerModule, DevExpress.Web.vX.Y, Version=X.Y.Z.0, Culture=neutral, PublicKeyToken=b88d1754d700e49a" name="ASPxHttpHandlerModule"/>  
    </httpModules>  
</system.web>

    IIS7 (integrated mode)

    <system.web>  
    <httpHandlers>  
        <add type="DevExpress.Web.ASPxHttpHandlerModule, DevExpress.Web.vX.Y, Version=X.Y.Z.0, Culture=neutral, PublicKeyToken=b88d1754d700e49a" verb="GET"  
        path="DX.ashx" validate="false" />  
    </httpHandlers>  
    <httpModules>  

    </httpModules>  
</system.web>  

<system.webServer>  
    <validation validateIntegratedModeConfiguration="false" />  
    <handlers>  
        <add type="DevExpress.Web.ASPxHttpHandlerModule, DevExpress.Web.vX.Y, Version=X.Y.Z.0, Culture=neutral, PublicKeyToken=b88d1754d700e49a" verb="GET" name="ASPxHttpHandlerModule"  
        path="DX.ashx" preCondition="integratedMode" />  
    </handlers>  
    <modules>  
        <add type="DevExpress.Web.ASPxHttpHandlerModule, DevExpress.Web.vX.Y, Version=X.Y.Z.0, Culture=neutral, PublicKeyToken=b88d1754d700e49a" name="ASPxHttpHandlerModule"/>  
    </modules>  
</system.webServer>

  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:

    • WebResource.axd (for standard handlers);
    • DXR.axd (for the DevExpresss ASPxHttpHandlerModule).

See Also