How do we resolve a 'deduplication' error received during the import process?

Environment:

All Versions

Issue:

We are receiving the following error from the data import wizard:

"Prescan Error: Unable to perform record deduplication.  Please ensure that your duplicate criterion matches a unique record for each import row."

Resolution:

This error is thrown when one of the rows in the import file matches more than one record which exists in the database, according to the duplicate criterion specified in the data import wizard.

To resolve this, either the record(s) in the database, or those in the data import file must be changed.  Steps to resolve are as follows:

1.  Export records from the databases as a csv file

2.  Import the database records into a Microsoft Excel Workbook

3.  Import the data import file into the same Microsoft Excel Workbook

4.  Using the match function, and the duplicate criteria which you will be using in the data import wizard, identify any matches between database records and the data import file.

5.  For any data import record which matches more than one database record, correct either the row in the data import, or the relevant fields in the database (via the console).

6.  After all changes have been made, import the (new) data file.

For information on other import errors, refer to Answer ID 6209: Data Import Wizard error messages.