I had a problem at work which I solved, but that raised me another question.
I wanted to export a page to excel, so I used this:
It worked but while I was searching for an answer I found 3 possible content types for the excel:
What is the correct, registered MIME Content-Type for Excel files?
so don't use any of these:
Why only this: application/vnd.ms-excel is correct and those are not: