I have a service that accesses a VB6 COM component on a timer event.  On 
64-bit windows (running in 32-bit "mode") the process fails if it is run in 
a secondary thread but works fine when run on the main thread.  This 
behavior cannot be re-produced in 32-bit environment.

Any help would be greatly appreciated.

The error is:

System.InvalidCastException: Unable to cast COM object of type 'blah.type' 
to interface type 'blah.interfacetype'. This operation failed because the 
QueryInterface call on the COM component for the interface with IID 
'{[guid....]]}' failed due to the following error: Error loading type 
library/DLL. (Exception frm HRESULT: 0x80029C4A (TYPE_E_CANTLOADLIBRARY)).

The exact code from the same components runs fine in 64-bit environment 
(again running in 32-bit mode) if it is not run on a secondary thread.

I'm not using a primary interop assembly and nothing is running from the GAC 
except framework stuff.

thanks,
-chris

I should mention:  All code is C# targeting x86 cpu using framework 2.0

i have a "fairly" simple example that demonstrates the problem.

-chris

"Chris Yager" <chris.yager@gldsolutions.com.invalid> wrote in message 
news:Oy5gujE3HHA.4184@TK2MSFTNGP06.phx.gbl...

>I have a service that accesses a VB6 COM component on a timer event.  On 
>64-bit windows (running in 32-bit "mode") the process fails if it is run in 
>a secondary thread but works fine when run on the main thread.  This 
>behavior cannot be re-produced in 32-bit environment.
>
> Any help would be greatly appreciated.
>
> The error is:
>
> System.InvalidCastException: Unable to cast COM object of type 'blah.type' 
> to interface type 'blah.interfacetype'. This operation failed because the 
> QueryInterface call on the COM component for the interface with IID 
> '{[guid....]]}' failed due to the following error: Error loading type 
> library/DLL. (Exception frm HRESULT: 0x80029C4A (TYPE_E_CANTLOADLIBRARY)).
>
> The exact code from the same components runs fine in 64-bit environment 
> (again running in 32-bit mode) if it is not run on a secondary thread.
>
> I'm not using a primary interop assembly and nothing is running from the 
> GAC except framework stuff.
>
> thanks,
> -chris
> 

>I have a service that accesses a VB6 COM component on a timer event.  On 
>64-bit windows (running in 32-bit "mode") the process fails if it is run in 
>a secondary thread but works fine when run on the main thread.  This 
>behavior cannot be re-produced in 32-bit environment.
>
>Any help would be greatly appreciated.



I'm guessing the thread has the wrong ApartmentState.


Mattias

-- 
Mattias Sjgren [C# MVP]  mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.

I'd considered that but it behaves well in 32-bit windows.

thanks for the response,
-chris

"Mattias Sjgren"  wrote in message 
news:e4p2A8S3HHA.1184@TK2MSFTNGP04.phx.gbl...

>
>>I have a service that accesses a VB6 COM component on a timer event.  On
>>64-bit windows (running in 32-bit "mode") the process fails if it is run 
>>in
>>a secondary thread but works fine when run on the main thread.  This
>>behavior cannot be re-produced in 32-bit environment.
>>
>>Any help would be greatly appreciated.
>
>
> I'm guessing the thread has the wrong ApartmentState.
>
>
> Mattias
>
> -- 
> Mattias Sjgren [C# MVP]  mattias @ mvps.org
> http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
> Please reply only to the newsgroup. 

Hi Chris,

the error message indicates that the typelib cannot be loaded - can you 
load it manually using LoadRegTypeLib (on 64-bit windows) or do you get 
the same error?

--Johannes

Chris Yager wrote:

> I'd considered that but it behaves well in 32-bit windows.
> 
> thanks for the response,
> -chris
> 
> "Mattias Sjgren"  wrote in message 
> news:e4p2A8S3HHA.1184@TK2MSFTNGP04.phx.gbl...
>>> I have a service that accesses a VB6 COM component on a timer event.  On
>>> 64-bit windows (running in 32-bit "mode") the process fails if it is run 
>>> in
>>> a secondary thread but works fine when run on the main thread.  This
>>> behavior cannot be re-produced in 32-bit environment.
>>>
>>> Any help would be greatly appreciated.
>>
>> I'm guessing the thread has the wrong ApartmentState.
>>
>>
>> Mattias
>>
>> -- 
>> Mattias Sjgren [C# MVP]  mattias @ mvps.org
>> http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
>> Please reply only to the newsgroup. 
> 
> 



-- 
Johannes Passing - http://int3.de/

Thanks to all for the help.
The problem was the apartment state.

I spawned an additional thread off the timer's thread and set the apartment 
state to "STA" and everything works as expected.

Thanks again,
-chris

"Mattias Sjgren"  wrote in message 
news:e4p2A8S3HHA.1184@TK2MSFTNGP04.phx.gbl...

>
>>I have a service that accesses a VB6 COM component on a timer event.  On
>>64-bit windows (running in 32-bit "mode") the process fails if it is run 
>>in
>>a secondary thread but works fine when run on the main thread.  This
>>behavior cannot be re-produced in 32-bit environment.
>>
>>Any help would be greatly appreciated.
>
>
> I'm guessing the thread has the wrong ApartmentState.
>
>
> Mattias
>
> -- 
> Mattias Sjgren [C# MVP]  mattias @ mvps.org
> http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
> Please reply only to the newsgroup.