diff --git a/spiffworkflow-backend/src/spiffworkflow_backend/models/process_instance_event.py b/spiffworkflow-backend/src/spiffworkflow_backend/models/process_instance_event.py
index 684c9e086..3a883e5c3 100644
--- a/spiffworkflow-backend/src/spiffworkflow_backend/models/process_instance_event.py
+++ b/spiffworkflow-backend/src/spiffworkflow_backend/models/process_instance_event.py
@@ -39,7 +39,9 @@ class ProcessInstanceEventModel(SpiffworkflowBaseDBModel):
 
     user_id = db.Column(ForeignKey(UserModel.id), nullable=True, index=True)  # type: ignore
 
-    error_details = relationship("ProcessInstanceErrorDetailModel", cascade="delete")  # type: ignore
+    error_details = relationship(
+        "ProcessInstanceErrorDetailModel", back_populates="process_instance_event", cascade="delete"
+    )  # type: ignore
 
     @validates("event_type")
     def validate_event_type(self, key: str, value: Any) -> Any: