the support case is the correct option.
It is to assume that the query used for this contains attributes or criteria's no longer existing (or moved) after upgrading.
Which, or if some other issue, will be investigated within the case.
We introduced a signature attribute where staff can insert along with an IT logo. The attribute was inserted as a field on reminders/notifications when communicating with the customer to make messages more personalised.
Since upgrading to 2017.1 we noticed this error, removing the image from staff's signatures seemed to resolve this issue.
We have now come across this issue again for which we have logged a support call, on this occasion, it is not signature related, I suspect it is to do with images as the ticket description has lots of text with broken images. However, there is no workaround and we can't close off the ticket.