File Format or File Extension is not valid ????

[Kelly0208]

I am trying to open an excel file. The message I am getting reads, "Excel cannot open the file because the file format or file extension is not valid. Verify that the file has not been corrupted and that the file extension matches the format of the file." This file is saved on a jump drive. I have tried all the different tricks listed to  

[#2]

@Kelly0208 

I have a file I routinely export from an outside source for the purpose of importing (opening) in Excel. When I go to open it, it always gives me this alert, and I'm wondering if yours is the same.

Now, in my case, I do trust the source completely, so I just click on "Yes" and it opens and that ends it. All I'm doing, in my situation, is extracting some data from that file, so once I've used it for its purpose, it gets overridden by the next instance, and so on. The message is a warning for your own safety, so it's up to you to decide whether or not the file is trusted.