Apologies for the long post but I have been at this now for a couple days and nothing I've found searching blogs, forums, msdn, and so on has helped so I wanted to give as much info as possible when asking for any ideas/help. The full error message I am getting is this:
"Excel cannot open the file 'SomeFileName.xlsx' because the file format or file extension is not valid. Verify that the file has not been corrupted and the file extension matches the format of the file."
I'll include code below. Here's the problem: I'm trying to get a download to open up as a file with a ".xlsx" file extenstion when downloaded to Excel. First the content type and extension combinations...
Content Type :: File Extension
application/vnd.ms-excel :: .xls --> works, I can open the file though there is a warning that the extension does not match the type.
application/vnd.ms-excel :: .xml ...
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