Cannot get property 'label' on null object

ISSUE

Your task is failing with the error "
Cannot get property 'label' on null object"

CAUSE

The error means that dataloader.io is not able to retrieve a field/object that it was previously able to retrieve when the task was created.

After losing access (for any reason) to that field/object, but still trying to query it (because the query was not updated), it fails to find the field/object.

SOLUTION

The easiest solution for this issue is to create a new task and replicate the configuration, this way, you will only be able to add to the query the fields/objects that are currently available.

Another option is to uncheck all the fields from the list in the task wizard and then select the needed fields again. In case you created the query manually, you will need to reset the query and create it again.