diff --git a/spiffworkflow-backend/poetry.lock b/spiffworkflow-backend/poetry.lock
index bafd38151..f3cd51d12 100644
--- a/spiffworkflow-backend/poetry.lock
+++ b/spiffworkflow-backend/poetry.lock
@@ -1,4 +1,4 @@
-# This file is automatically @generated by Poetry 1.8.3 and should not be changed by hand.
+# This file is automatically @generated by Poetry 1.8.1 and should not be changed by hand.
 
 [[package]]
 name = "alembic"
@@ -2986,7 +2986,7 @@ doc = ["sphinx", "sphinx_rtd_theme"]
 type = "git"
 url = "https://github.com/sartography/SpiffWorkflow"
 reference = "main"
-resolved_reference = "14c84aa26d0485753ed8f174d69fb12a888c455a"
+resolved_reference = "579bac49ea3d3e52d3942c3c4bcda1ae4500285e"
 
 [[package]]
 name = "spiffworkflow-connector-command"
diff --git a/spiffworkflow-backend/src/spiffworkflow_backend/services/workflow_execution_service.py b/spiffworkflow-backend/src/spiffworkflow_backend/services/workflow_execution_service.py
index bdc911b6b..3357ed8e3 100644
--- a/spiffworkflow-backend/src/spiffworkflow_backend/services/workflow_execution_service.py
+++ b/spiffworkflow-backend/src/spiffworkflow_backend/services/workflow_execution_service.py
@@ -62,6 +62,19 @@ class WorkflowExecutionServiceError(WorkflowTaskException):  # type: ignore
             error_line=workflow_task_exception.error_line,
         )
 
+    @classmethod
+    def from_completion_with_unhandled_events(
+        cls,
+        task: SpiffTask,
+        unhandled_events: dict[str, list[Any]],
+    ) -> WorkflowExecutionServiceError:
+        events = {k: [e.event_definition.code for e in v] for k, v in unhandled_events.items()}
+
+        return cls(
+            error_msg=f"The process completed with unhandled events: {events}",
+            task=task,
+        )
+
 
 class ExecutionStrategyNotConfiguredError(Exception):
     pass
@@ -533,7 +546,7 @@ class WorkflowExecutionService:
             if self.bpmn_process_instance.is_completed():
                 self.process_instance_completer(self.bpmn_process_instance)
 
-            self.process_bpmn_messages()
+            self.process_bpmn_events()
             self.queue_waiting_receive_messages()
             return task_runnability
         except WorkflowTaskException as wte:
@@ -585,14 +598,28 @@ class WorkflowExecutionService:
                         queued_to_run_at_in_seconds=queued_to_run_at_in_seconds,
                     )
 
-    def process_bpmn_messages(self) -> None:
-        # FIXE: get_events clears out the events so if we have other events we care about
-        #   this will clear them out as well.
-        # Right now we only care about messages though.
-        bpmn_events = self.bpmn_process_instance.get_events()
+    def group_bpmn_events(self) -> dict[str, Any]:
+        event_groups: dict[str, Any] = {}
+        for bpmn_event in self.bpmn_process_instance.get_events():
+            key = type(bpmn_event.event_definition).__name__
+            if key not in event_groups:
+                event_groups[key] = []
+            event_groups[key].append(bpmn_event)
+        return event_groups
+
+    def process_bpmn_events(self) -> None:
+        bpmn_event_groups = self.group_bpmn_events()
+        message_events = bpmn_event_groups.pop(MessageEventDefinition.__name__, [])
+
+        if bpmn_event_groups and self.bpmn_process_instance.is_completed():
+            raise WorkflowExecutionServiceError.from_completion_with_unhandled_events(
+                self.bpmn_process_instance.last_task, bpmn_event_groups
+            )
+
+        self.process_bpmn_messages(message_events)
+
+    def process_bpmn_messages(self, bpmn_events: list[MessageEventDefinition]) -> None:
         for bpmn_event in bpmn_events:
-            if not isinstance(bpmn_event.event_definition, MessageEventDefinition):
-                continue
             bpmn_message = bpmn_event.event_definition
             message_instance = MessageInstanceModel(
                 process_instance_id=self.process_instance_model.id,