This error occurs when the donation in question is a TeamRaiser gift to a participant who has not yet had their TeamRaiser registration synced to Raiser's Edge.  

To resolve, you would need to determine why the registration has not synced. When viewing the details of the error, click the link next to Online ID: to be redirected to the Transactions page. The Transaction ID should be autopopulated. Click Search to find out more information about the transaction in question. Once the participant has been synced between the two systems, you can Rebuild the error