This message will be shown if the program was unable to create tracks for the participant in the Zencastr database. Most likely this is due to an unexpected drop out in the network connection at the time of the save.
We are working on handling this error more gracefully in the near future. But in the meantime, having the participant refresh the page should cause the application to retry creating the necessary tracks. If that still doesn't work. Creating a new episode as the host and inviting the participant to join this new recording should help work around this issue.