Design-Time Errors Occur on a Page Using Telerik Controls
|Product||Progress® Telerik® UI for ASP.NET AJAX|
When working with Telerik UI for ASP.NET AJAX or dragging a Telerik control from the ToolБox to the design surface, design-time errors occur on a page that uses Telerik controls.
Depending on the use case, the possible causes for such errors may be the following:
Telerik.Web.UI.dllassembly is updated while a page using Telerik controls is in Design-time, Visual Studio creates two different versions of the assembly. Hence, two different versions of the same Telerik controls are available.
If you try to drag a Telerik control from the Toolbox to the design surface and get an error, the possible reasons are various. Refer to the resource links below.
After upgrading Telerik UI for ASP.NET AJAX to Q1 2009, Visual Studio 2008 has a problem with loading GAC-ed design-time assemblies of control libraries deployed in the
Binfolder of a website.
(Two assembly versions)
Error Creating Control - Telerik control 'Property' cannot be initialized. Details: Unable to cast object of type 'Type' to type 'Type'
(Dragging a Telerik control from the ToolBox)
Error creating control. Unable to cast object of type 'Telerik.Web.UI.Radxxx' to type 'Telerik.Web.UI.ControlItemContainer
(Problem loading GAC-ed assemblies)
Error creating control - ControlNameor
Failed to create designer "Telerik.Web.UI.ControlName..."
Depending on the possible cause for this issue, use the following approaches to handle it:
(Two assembly versions) Restart Visual Studio.
(Dragging a Telerik control from the ToolBox) Refer to the following resources:
(Problem loading GAC-ed assemblies) To solve this issue, use any of the following approaches:
Bin-deploy the design-time assembly, add a reference to
Telerik.Web.Design.dllto your website or application, remove
Telerik.Web.Design.dllfrom the GAC, and restart Visual Studio.
To GAC-deploy the control library assembly, add
Telerik.Web.UI.dllin the GAC, remove
Binfolder, and restart Visual Studio.
C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE\PublicAssembliesand restart Visual Studio.