When trying to process event transactions in the Online Express plugin either via bulk processing or individually this error is generated when the event that was linked to the form at the time the transaction was entered into the form has been deleted from within Raiser's Edge.
Please contact support with the following information:
1. The date of the last transaction your organization was able to download 2. A screenshot of File>Properties of the event record in RE
Steps to Duplicate
1. Set up an event form in Online Express that is linked to an event 2. Have transactions entered into the live form on your website while it is linked to this event 3. Delete the event from Raiser's Edge and link the form to another event 4. Attempt to process transactions that were entered into the form when it was linked to the first event.