How to Resolve Quickbooks Interface Error: QBFC Error “Could Not Load File or Assembly Interop.QBFC7 or one of its dependencies”

Question

I recently inherited a C# Winforms application that communicates with Quickbooks via their QBFC interface. The application contains a reference to the COM Server Interop.QBFC7.dll. The application works fine in our test environment and in several of our client's environments. Although, yesterday when I attempted to install it on a new customer's system I continued to get the following error:

Could Not Load File or Assembly 'Interop.QBFC, Version=8.0.0.87, Culture=neutral, PublicKeyToken=...' or one of its dependencies. The system cannot find the file specified.

I know that we have several customers running this application on various versions of Quickbooks (i.e. Quickbooks Pro, Premier and Enterprise between 2008 and Enterprise 11.0). To my knowledge, this is the first customer that we have attempted to deploy this application that has Enterprise 12.0.

I have attempted the following to resolve the issue with no success:

1) Install the QBFC7_Installer from the Intuit Developer Network Site
2) Install the Quickbooks SDK 10 Installer from the Intuit Developer Network Site
3) Verified that the Interop.QBFC7.dll file is present on the file system.
4) Attempted to manually register the COM object Interop.QBFC7.dll via the command prompt: regsvr32 Interop.QBFC7.dll (This fails as well and windows returns an error stating that it cannot find the object).

Does anyone have any suggestions or feedback about additional things that I can try to resolve this issue? I get the same error on 3 different machines at their site running different operating systems (i.e. Windows Server 2008, Windows 7, and Windows Vista)? I have also tried compiling in both x86 and 64-bit configurations to no avail.

Thanks in advance for any help.

Answer 1

First of all, you should be targeting an x86 build only. The QuickBooks SDK won't work if you target Any CPU or x64. Your main problem, though, is that you are looking for the wrong version of QBFC. Notice the version stamp on your error message:

Could Not Load File or Assembly 'Interop.QBFC, Version=8.0.0.87, Culture=neutral, PublicKeyToken=...' or one of its dependencies. The system cannot find the file specified

This is QBFC8, not QBFC7. So you should be able to fix the problem with the QBFC8 installer.

The version of QuickBooks should not make a difference, since QBFC 8 (or 7, for that matter) will work with the 2008 and Enterprise 11 or 12.

You should look into using a setup project to install your application in order to avoid this problem in the future. A setup project should detect the QBFC dependency automatically. Once you see this happening, go to SearchPath property of your setup project and add the MergeModule directory from the SDK that is installed on your machine. Once you do this, you should see that the QBFC and Xerces merge modules are added to your project automatically as dependencies. Of course, you'll also need to update your code to a more recent version of QBFC, but that's probably a good idea in any case.