This error can arise if you try to put non-numeric data into a Number
type field, non-date data into a Date/Time field, etc.
Note that Date/Time fields are pretty strict about syntax; ideally you
should insert dates in mm/dd/yyyy format delimited by # characters. If
you just try to insert 6/2 it might assume you're doing a division and
trying to insert 3 into the date field!