The dates in your file do not match the date format selected. The selected date order was: Month, day, year
Your file can be processed with dates in the following orders:
Check the date format used in your file, and select it on the “Upload your file” screen.

The error message states that the issue is due to the dates in your file do not match the date format selected.
If after checking that the date format was indeed correct, another reason could be that you have an empty/blank cell in one (or more) of your transaction's description.
Review your import file and ensure you do not have a blank/empty description field on any rows.
EXAMPLE:
Here is an example of a file that would fail the import and give the error message

Here is the same file corrected that would not fail:

TIP: If you have a transaction with no description, instead of leaving it empty, we recommend typing in the words "no description" for example in the field, or anything else you would like, as long as it's not empty for the import to succeed.