The actual projects structure is:
+ MyServerFramework
|---QueryComponent.cs
...
+ MyServerFramework.Design
|---QueryComponentDesigner.cs
...

The MyServerFramework.Design project has a reference to MyServerFramework, and is compiled alone in its own solution which also contains MyServerFramework, and then placed in a folder that is referenced the SOFTWARE\Microsoft\.NETFramework\AssemblyFolders key so the IDE can find it.

The MyServerFramework project is then used in other solutions which don't contain the MyServerFramework.Design assembly. And here is where I'm seeing this error.

This happens in the following line, which is in the verb handler in QueryComponentDesigner:

QueryBuildStorProcDialog dlg = new QueryBuildStorProcDialog((QueryComponent)this.Component);

I've checked this at runtime with the debugger and this.Component IS of type QueryComponent.

Since it can't cast an object of a type to EXACTLY THE SAME TYPE, I guess either the error message is wrong or the problem lies in some versioning problem. Neither of the assemblies are strong-named, and I've tried changing the reference method: adding MyServerFramework.Design to the solution and referencing it as a project, referencing it by file name (Browse... in the add reference dialog), and adding it to the AssemblyFolders folder).

Is it possible the IDE is caching a previous version of my .Design assembly and using it instead of the current one (that it should find through the reference in the project or in the AssemblyFolders folder?

I just can't believe there's noone at Microsoft being able to answer these questions, I just hope they are busy trying to come up with some solutions to the myriad of problems in VS2005.

This particular problem apparently arises because of several factors:
The IDE caches versions of assemblies in the following folder:

"x\Documents and Settings\user\Local Settings\Application Data\Microsoft\VisualStudio\8.0\ProjectAssemblies"

And at least in my case doesn't detect the particular assembly containing the type has a new version and it doesn't update the cache.

If you attach to a running instance of VS2005 and check what Modules are loaded (you may need to add the Modules window command from the Debug category in Tools > Customize...) you'll probably see two versions of your assembly are loaded, or even the same version of the assembly loaded twice: in both cases you'll see the same error message.

So first step, delete all folders in ProjectAssemblies. Next, make sure the IDE can only find ONE copy of your assembly, which is easier if you only have one copy of the DLL in your disk, and only one reference to it (or exactly the same reference from all projects) in your solution.

I have similar problems, see this post:

http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=160432&SiteID=1

I just can't believe there's noone at Microsoft being able to answer these questions, I just hope they are busy trying to come up with some solutions to the myriad of problems in VS2005.

This particular problem apparently arises because of several factors:
The IDE caches versions of assemblies in the following folder:

"x\Documents and Settings\user\Local Settings\Application Data\Microsoft\VisualStudio\8.0\ProjectAssemblies"

And at least in my case doesn't detect the particular assembly containing the type has a new version and it doesn't update the cache.

If you attach to a running instance of VS2005 and check what Modules are loaded (you may need to add the Modules window command from the Debug category in Tools > Customize...) you'll probably see two versions of your assembly are loaded, or even the same version of the assembly loaded twice: in both cases you'll see the same error message.

So first step, delete all folders in ProjectAssemblies. Next, make sure the IDE can only find ONE copy of your assembly, which is easier if you only have one copy of the DLL in your disk, and only one reference to it (or exactly the same reference from all projects) in your solution.

The story is not new -- this is the same behaviour as in 2002/2003. An additional source of problems is the "Local Copy" property of references: Even if the same dll is copied and then loaded from a different location, its types differ from those of the original dll.

Just make a test: At the point where the types are found to be different compare _all_ their attributes (after all types are just objects and they can differ only if their attributes differ). Print them out. You will see exactly the difference, that matters.

HTH,

D.Raiko

Yes, I don't recall having this problem with the ProjectAssemblies folder, but then again I didn't work too much on the design-time area... was it there too?

In any case, I think this is aggravated on 2005 because they also automatically add components in projects to the toolbar, which I suspect adds another binding to the cache or another cache alltogether, augmenting the chances of caching an old version.

I wonder if they do the correct thing in the DataSources window model or we have the same problems there...

I had the"unable to cast from x to x" error when the designer tried to load my main form which contained acustom control. If I simply put the cast within a try-catch block, everything worked fine. Note, the code never hit the catch block, so i don't know why that hack works, but it has held up so far.

-Tony

tony_held@yahoo.com

Hi and THANKS a lot in advance.

I'm getting this error in a different scenario, and I'm in a big urge to get this done, so please MS people and guys of the forum, any help is greatly appreciated.

I'll use a simplified scenario of my case, but the error happens the same. I'm creating a new User Control, I add a DataGridView to it, that's the only control in it.  I then create a public property called "Columns" to expose the DataGridView Columns property so I can access the property to the Desingner Editor.  I do that this way:

I took all that Attributes code from the System.Windows.Forms.DataGridView metadata, just as the Columns property appears in it.

Then, I add a Windows Forms item to my application and drag&drop one MyUC control from the toolbox into it.  Then I click the MyUC and go to its properties page to modify the Columns properties just as with an ordinary DataGridView.  The property is there but when clicking on its "..." button to open de Edit Columns Dialog I get the mentioned error.  Something like this:

"Unable to cast object of type 'WindowsApplication3.myUC" to type "System.Windows.Forms.DataGridView".

I tried what you have mentioned but it doesn't work. I still get this error.

I really really need the Columns property to be accesible in Desing Time this way.  I don't know how to work this out.

As I said, I get this error with an almost blank project.  Just add a User Control Item, put a DataGridView into it. Ade the code above to make the Columns property visible and then try to access the property in the Property page. 

Thank you so much in advance.

Fernando.

 PD: I'm using the shipped VS.NET 2005.

1. Miss References, ie referencing one and IDE loding different or something like that, due to different version of COM object loaded in Registry from different location.
2. Threading: Some COM dont support threading. So remove that class from any threading and test in console application. We will know the reason.

Hi, I encounter exactly the same problem with VS 2008 (C#).

Without the attributes, the designer to change the columnswill open but not save the changes in the code.

With the attributes, I get the 'Can not cast'-error.

Did you ever find a solution for this problem? Thanks for your answer!!!

Karsten

[Editor("System.Windows.Forms.Design.DataGridViewColumnCollectionEditor, System.Design, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a", typeof(UITypeEditor))]

[MergableProperty(false)]

[DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]

public DataGridViewColumnCollection DataGridColumns

get { return MyDataGrid.Columns; }

Close your VS2005 IDE windows. Start/Run "IISRESET" and this problem should go away. Mine did.

hi I Load Report.Rdlc into XMLDocument and Save it(in XML). it Save Successfully but when I read that XML it shows

{"The table (ReportItems) cannot be the child table to itself in nested relations."} Error.how could I solve?. it's urgent. My main Objective is I want to Customize Rdlc. I want to display Column(s) on the user's choice. Suppose I have 10 Columns. I want to give rights to user that how many column he want to display on theReport

try

try

finally

DataSet1TableAdapters.CustomersTableAdapter da = new DataSet1TableAdapters.CustomersTableAdapter();

finally

Imports System.ComponentModel

Public Class UserControl1

Inherits DataGridView

Private _grid As New DataGridView()

Private _alfa As New System.Windows.Forms.DataGridViewColumnCollection(_grid)

<Editor("System.Windows.Forms.Design.DataGridViewColumnCollectionEditor, System.Design", GetType(System.Drawing.Design.UITypeEditor))> _

Public ReadOnly Property Alfa() As System.Windows.Forms.DataGridViewColumnCollection

Get

Return _alfa

End Get

End Property

End Class

Hi, I encounter exactly the same problem with VS 2008 (C#).

Without the attributes, the designer to change the columnswill open but not save the changes in the code.

With the attributes, I get the 'Can not cast'-error.

Did you ever find a solution for this problem? Thanks for your answer!!!

[Editor("System.Windows.Forms.Design.DataGridViewColumnCollectionEditor, System.Design, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a", typeof(UITypeEditor))]

[

MergableProperty(false)]

[

DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]

public DataGridViewColumnCollection DataGridColumns

{

get { return MyDataGrid.Columns; }
}