Anyone who often works with CSV exports programmatically may have had this issue before, and I am sure that you may have been confused about what is causing it. You may have gotten one of the below, or both.

Error message one:

Excel has detected that ‘exported_file.csv’ is an SYLK file, but cannot load it. Either the file has error or it is not a SYLK file format. Click OK to try to open the file in a different format.

Error message two:

SYLK: File format is not valid

The good news is that it has a very simple solution:

If the first letters of the file is “ID”, you will get this problem. In my case, I had to rename the column header from “ID” to “Record ID” to solve the problem.

View the solution directly on Microsoft’s website. They suggest that you can also change “ID” to “id”. For me, that was not an option; I am pedantic about writing style in my reports. There is also a suggestion to add an apostrophe. Also viable, but my solution works easier for me. Do whatever works best for you!