This error is usually caused when the data you are trying to insert does not match the data type of the database field. This could be a text value being inserted into a number or date field, or a text value that is longer than the maximum length of the field.
To avoid this error, be sure to use the correct Field Type and/or Template on the Index tab to force the user to enter data in the correct format. You may also need to adjust the data types or lengths for your database fields.