When attempting to import a CSV contact list using the import option in the Address Book, the following error is displayed:
"system.exception:index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index' displays after providing a list name, description, selecting the file and importing under the outlook file type."
CSV or Excel files can only be imported under the custom file type in the import dialog menu.
Re-import the file using the custom method for this file type.
UPDATED: November 02, 2020