These Columns Don't Currently Have Unique Values

Error Example:

List update failed. These columns don't currently have unique values

Cause:

This can be caused by selecting a field or combination of fields that are not unique values for the Primary Key field. It will run a check on them to verify the uniqueness of value and cancel the list update if they are not.

Resolution/Workaround:

You should verify your Primary Key field(s) are all unique values in the source, and made adjustments to the data to remove duplicates or change the key field itself if it was a poor choice. It may also be due to truncation of values (making them no longer unique) or improperly set uniqueness constraints on columns.