In the error message, find the id marked [YYYYY] above. This is most likely a donation record. As part of associating the contact with a new household, the donation needs to be moved from one household to another, and this is causing the error. To resolve it:
  1. Manually move the donation to the correct household, using the existing household contact as the donor
  2. Complete associating the desired contact with the household
  3. Return to the donation and re-enter the correct donor