Dataflow error: "Error accessing replicated dataset.: Invalid extract field name."

This error occurs because CRM Analytics tried to read a field from a replicated dataset that was not included in the most recent Data Sync run. Data Sync is the process that copies Salesforce object data into CRM Analytics for use in Dataflows. Rerunning the Data Sync again updates the data Dataflow depends on, ensuring the expected field is available before the Dataflow executes.
 

Check Data Sync Contents

1. In Data Manager, access the Connect screen.
2. Click the Object which contains the field.
3. Ensure the field exists in the Connected Dataset structure and is not deactivated (grayed out). If you're unable to save any changes and the Save button is grayed out, refer to this article.
Or
4. If you have decided to remove the field from the replicated object dataset, proceed with the following steps.

Run Data Sync

1. On the replicated object dataset, click Run Data Sync.
2. Confirm that Data Sync completes successfully.

Retry Dataflow

After Replication (including the specified field) has been completed, manually run the Dataflow.

More information about adding fields to Replication can be found in Add Salesforce Objects and Fields to Data Sync.