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V22.1

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: