[Koha] Internal server error with ISBD detail and making a hold on OPAC

I’m recently started to get internal server errors when looking at ISBD detail and making a hold when in the OPAC. We’re using Koha 19.11.22.000 on Debian 9. I’ve seen a similar problem reported as bug 22735: Resolve internal server error on missing item type but that was on 18.05 and presumably fixed back then. Can anyone offer any fixes please? Paul Leman -- Paul Leman