"This column mixes both date orders (day/month and month/day). Fix the file or set the column to “(ignore)”."

Where: Importing students screen, step 2 (Match the columns), after mapping a column to Enrollment date (/students/import).

Why: in this column, at least one date looks like a day greater than 12 (for example 25/03/2020, read day/month) and at least one other looks like a month greater than 12 (for example 03/25/2020, read month/day). The app cannot guess the order: reading the column a single way would give wrong dates.

What to do: fix the column in the file so all its dates follow the same order, then run the import again. If the column is not useful, map it to (ignore). If the order is simply reversed from end to end (no contradiction), use the Swap day and month button in the preview instead.