Symptoms
From Visual Basic, when trying to specify a field Format property of anAccess table (for example, field type DateTime) from blank to “Long Date”format, the following error occurs:

Run-time error ‘3421′:
Data type conversion error.
Resolution
The property data type constant should always be “dbText.” If other datatype constants, such as dbDate or dbNumeric are specified, you willencounter the error described above.