[Koha] Need help resolving error on item search in Koha 17.11

Hello, We are seeing the following error when doing an "item search" in Koha 17.11. We've tried searching on barcode and on author but always see the same message. Our training system (running Koha 17.05) does not show this error. Is this a bug or are we perhaps doing something wrong? Thanks! Chris Brown Software error: Unsupported format html at /usr/share/koha/intranet/cgi-bin/catalogue/itemsearch.pl line 42.