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COM+ error System.InvalidCastException

Posted on 2004-08-31
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Last Modified: 2012-06-27
Hi All,
 I have a COM component that i have installed as a server component. I create an instance of the component in my .aspx file. It worked fine for some time, then i changed another component that the com calls and i started getting a message
System.InvalidCastException: Specified cast is not valid
[InvalidCastException: Specified cast is not valid.]
   System.Runtime.InteropServices.Marshal.ThrowExceptionForHR(Int32 errorCode, IntPtr errorInfo) +0
   System.EnterpriseServices.Thunk.Proxy.CoCreateObject(Type serverType, Boolean bQuerySCInfo, Boolean& bIsAnotherProcess, String& uri) +581
   System.EnterpriseServices.ServicedComponentProxyAttribute.CreateInstance(Type serverType)
   System.Runtime.Remoting.Activation.ActivationServices.IsCurrentContextOK(Type serverType, Object[] props, Boolean bNewObj) +74
   intersoft.ptList.WebGrid1_InitializeDataSource(Object sender, DataSourceEventArgs e) in c:\inetpub\wwwroot\uilayer\ptlist.ascx.cs:179
   ISNet.WebUI.WebGrid.WebGrid.OnInitializeDataSource(Object dataSource)
   ISNet.WebUI.WebGrid.WebGrid.OnLoad(EventArgs e)
   System.Web.UI.Control.LoadRecursive()
   System.Web.UI.Control.LoadRecursive()
   System.Web.UI.Control.LoadRecursive()
   System.Web.UI.Control.LoadRecursive()
   System.Web.UI.Page.ProcessRequestMain()

Can somebody help me with this problem,
Thanks,
Preetham.
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Question by:kingpreetham
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Accepted Solution

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NipNFriar_Tuck earned 50 total points
ID: 11953561
There is a good possibility that when you changed the code the GUID for the class changed.  You can prevent this from happening by adding a GUID attribute [GUID("###")] to the classes and interfaces used in the com piece also in the code that the com piece calls...

Another possiblity is of the namespace changed then even though the class is exactly the same you will not be able to cast from one to another...

Anyhow, these are two situations that I have ran into that may explain what is happening to you...
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