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We have an Excel Add-In written in C++ that has been working correctly with 32-bit Excel for some time.
I re-compiled it as a 64-bit dll but Excel says it is not a valid add-in.
The Dependency walker reports a long list of missing dlls that all seem to be part of Windows API. e.g API-MS-WIN-EVENTING-PROVIDER-L1-1-0.DLL.
The Add-In dll was built with Visual Studio 2019. The toolset is v142.
Microsoft Visual C++ 2015-2019 Redistributable (x64) - 14.29.30038 is installed on the PC.
I suspect the solution to this problem is just a setting in the IDE. Can anyone tell me what to do?
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The old dependency walker can be confused - check your dependencies with an updated tool such as Dependencies.
Did you make sure to re-register the add-in so that excel finds the 64-bit dll and not a pre-existing 32-bit dll?
When I try to register the Add-In with Excel it responds that the dll file "... is not a valid add-in".
I mean the COM registration so that the correct entries are set in the 64-bit view of the registry.
I am obviously missing something here. I checked the Registry and the only places this file is listed is in Dependency recent files and Excel AddInLoadTimes. Excel Add-In Manager key is empty.
Since you mentioned C++ I assume that you are referring to an unmanaged COM add-in. In addition to the usual registry entries for a COM object, the progid of your add-in should be present in the 64-bit view of the registry under HKLM or HKCU Software\Microsoft\Office\Excel\Addins\<Use your Progid> with an entry specifying "LoadBehavior" that is usually set to a REG_DWORD value of 3.
I don't have an Excel\Addins key in either HKLM or HKCU. But I don't have any Add-Ins registered with this Excel. The dll I am trying to add is reported as "not valid" so I have stopped at that point. If I proceed, it tries to open the dll as a worksheet.
I didn't write this add-in and the author is no longer available. All I know is that it works with 32-bit Excel. If you could direct me to some instructions for preparing C++ Excel Add-Ins, that would be helpful. The websites I have tried to use are just broken links.
Is this add-in actually an XLL? If so then the reference material is here - welcome-to-the-excel-software-development-kit
I have never created an XLL add-in for Excel so I can't provide guidance for you if that is the case.
If the DLL is a COM add-in then it should export DllRegisterServer, DllGetClassObject and DllCanUnloadNow
Did you determine if the add-in is an XLL?
Dependencies reports 16 missing dll files as shown in the attached screenshot.
I doubt they're missing.
Is it reporting on any specific functions in those DLLs that aren't available?
Yes, each of these entries can be opened to display a long list of DLLs; probably the entire contents.
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I have just come across the same issue. Did you find a solution?