1. Please rebuild your project. If there are any compiler errors, they must be fixed prior to opening form designers.
2. If you use Visual Studio 2005 and have just installed a new version of our controls, please take a look at the following article:
How to resolve the design-time problem when opening forms in Visual Studio 2005 after updating DevExpress controls
3. If your project contains inherited forms or UserControls with DevExpress components and you've just upgraded your project from VS.NET 2002/2003 to VS 2005, please refer to this article:
How to enable visual inheritance for Developer Express controls
4. Make sure that the CopyLocal property of all references to the DevExpress.~ assemblies is set to False:
Component designers are unavailable at design time
5. Please locate the licenses.licx file in your project and clear it. Rebuild your project and try to open the form in design mode.
6. Try to use our VersionChecker tool to make sure that there are no old versions of the DevExpress.~ assemblies in the Assembly Cache (C:\WINDOWS\assembly). If old versions are present, they must be manually deleted. The VersionChecker is shipped with the DXperience suite and can be launched from Start Menu\Programs\Developer Express .NET v6.1\Tools. If you are using an older version of our controls, please click here to download the VersionChecker from our Web site.
If nothing of the above helps, please capture the error call stack as explained in the following article and send it to the Support Team. We will do our best to help you.
How to obtain a design-time exception call stack