First Time Importing Connection
If it's your first time importing into a connection field, we recommend that you start by reviewing this article: Importing Connections.
Importing Multiple Connections
If you're trying to import multiple values into a connection field, take a look at this article section: Importing to a Many-to-Many Connection Field.
Check the Connected Object
In order to connect a record in your import file to a record in a connected object, the connected record must already exist. For example, if you are importing a new Employee and want to connect them to the Sales department, the Sales department needs to already exist in the Departments object.
Check Your Matching
When connecting records through an import, you need to match one of the columns in your import file to one of the fields in the connected object. That way the system knows which connected record to connect to the record being created or updated by your import:
You need to make sure that you’re matching on a unique field in the connected object. Auto Increment fields are great for matching, though there are several field types that can be set to "Must be unique":
Note: We don’t recommend matching on a Name or Address field because they can’t be set to unique and we’ve seen users run into issues with them. We’re working on improving this for those field types.