Why can't Excel download excel-dna add-on?

Question

Error:

The file you are trying to open, "ExcelDna.xll", is in a different format than indicated in the file extension file. Make sure that the file is not corrupted and is from a trusted source before opening the file.

Answer 1

Yes - this is exactly the behavior that you get when the .xll add-in has the wrong bit for the Excel process. For Excel-DNA, you need to use a copy of ExcelDna.xll for 32-bit versions of Excel (runs on 32-bit or 64-bit versions of Windows) and a copy of ExcelDna64.xll for 64-bit versions of Excel 2010.

Note that on all versions of Windows (both 32-bit and 64-bit), the recommended and standard installation of Office is the 32-bit version.

Answer 2

I had exactly the same problem, but NOT due to the use of DNA64 . In my case, the problem occurred when I downloaded XLL from C:\Temp\[blah]\myXll.xll If I copied XLL (and related folders) to C:\Program Files (x86)\[blah]\ , then it worked fine.