Someone named Pablo Escobär on the Admins United discord saw LogRep: FRepLayout::UpdateChangelistHistory: History overflow, forcing history dump BP_NPC_Wildlife_TurtleMedium_Pet_C showing up repeatedly in his crash logs, so he used a SQL script to remove all of them from the actor_position and properties tables and it solved his crashes.

I’m not enthusiastic about running SQL scripts that remove things in my DB, but if deleting the building at C-9 hadn’t solved the problem for me, this would have been my next step.