C# – To prevent possible data loss in windows form c#

If i click to Form1.cs in windows form , i get below exception,

To prevent possible data loss before loading the designer , the
following errors must be resolved:

Loading this assembly would produce a different grant set from other
instances.(Exception from HRESULT 0x80131401)

Could not find type 'Gizmox.WebGUI.Forms.Form'. Please make sure that
the assembly that contains this type is referenced. If this type is a
part of your development project, make sure that the project has been
successfully built using settings for your current platform or Any
CPU.

Call Stack :

at
System.ComponentModel.Design.Serialization.CodeDomSerializerBase.Error(IDesignerSerializationManager
manager, String exceptionText, String helpLink) at
System.ComponentModel.Design.Serialization.TypeCodeDomSerializer.Deserialize(IDesignerSerializationManager
manager, CodeTypeDeclaration declaration) at
System.ComponentModel.Design.Serialization.CodeDomDesignerLoader.PerformLoad(IDesignerSerializationManager
manager) at
Microsoft.VisualStudio.Design.Serialization.CodeDom.VSCodeDomDesignerLoader.PerformLoad(IDesignerSerializationManager
serializationManager) at
Microsoft.VisualStudio.Design.Serialization.CodeDom.VSCodeDomDesignerLoader.DeferredLoadHandler.Microsoft.VisualStudio.TextManager.Interop.IVsTextBufferDataEvents.OnLoadCompleted(Int32
fReload)

Any help will be greatly appreciated.

Thanks.