[Koha] Error "500" on Opac

Being rather new to this list, I will apologize in advance if I'm mis-framing this question. After upgrading from Koha 20.05 to 21.05, I started receiving an HTTP 500 error when an OPAC user clicks on a specific title in the list returned by a catalog search. This does not occur when doing a catalog search on the staff pages. I have looked through the various Koha logs, but cannot find any errors pointing to a script, or anything. Any ideas and suggestions of where to look for the cause and resolution of this would be helpful. Many Thanks! Bruce Yelen