diff --git a/spiffworkflow-backend/src/spiffworkflow_backend/models/process_instance.py b/spiffworkflow-backend/src/spiffworkflow_backend/models/process_instance.py
index 1a4510b7..7af28170 100644
--- a/spiffworkflow-backend/src/spiffworkflow_backend/models/process_instance.py
+++ b/spiffworkflow-backend/src/spiffworkflow_backend/models/process_instance.py
@@ -34,36 +34,6 @@ class ProcessInstanceCannotBeDeletedError(Exception):
     """ProcessInstanceCannotBeDeletedError."""
 
 
-class NavigationItemSchema(Schema):
-    """NavigationItemSchema."""
-
-    class Meta:
-        """Meta."""
-
-        fields = [
-            "spec_id",
-            "name",
-            "spec_type",
-            "task_id",
-            "description",
-            "backtracks",
-            "indent",
-            "lane",
-            "state",
-            "children",
-        ]
-        unknown = INCLUDE
-
-    state = marshmallow.fields.String(required=False, allow_none=True)
-    description = marshmallow.fields.String(required=False, allow_none=True)
-    backtracks = marshmallow.fields.String(required=False, allow_none=True)
-    lane = marshmallow.fields.String(required=False, allow_none=True)
-    task_id = marshmallow.fields.String(required=False, allow_none=True)
-    children = marshmallow.fields.List(
-        marshmallow.fields.Nested(lambda: NavigationItemSchema())
-    )
-
-
 class ProcessInstanceStatus(SpiffEnum):
     """ProcessInstanceStatus."""
 
@@ -139,6 +109,10 @@ class ProcessInstanceModel(SpiffworkflowBaseDBModel):
         """Validate_status."""
         return self.validate_enum_field(key, value, ProcessInstanceStatus)
 
+    def can_submit_task(self) -> bool:
+        """Can_submit_task."""
+        return not self.has_terminal_status() and self.status != "suspended"
+
     def has_terminal_status(self) -> bool:
         """Has_terminal_status."""
         return self.status in self.terminal_statuses()
diff --git a/spiffworkflow-backend/src/spiffworkflow_backend/routes/process_api_blueprint.py b/spiffworkflow-backend/src/spiffworkflow_backend/routes/process_api_blueprint.py
index f2cb3e12..349af266 100644
--- a/spiffworkflow-backend/src/spiffworkflow_backend/routes/process_api_blueprint.py
+++ b/spiffworkflow-backend/src/spiffworkflow_backend/routes/process_api_blueprint.py
@@ -1670,6 +1670,13 @@ def task_submit(
     """Task_submit_user_data."""
     principal = find_principal_or_raise()
     process_instance = find_process_instance_by_id_or_raise(process_instance_id)
+    if not process_instance.can_submit_task():
+        raise ApiError(
+            error_code="process_instance_not_runnable",
+            message=f"Process Instance ({process_instance.id}) has status "
+            f"{process_instance.status} which does not allow tasks to be submitted.",
+            status_code=400,
+        )
 
     processor = ProcessInstanceProcessor(process_instance)
     spiff_task = get_spiff_task_from_process_instance(
diff --git a/spiffworkflow-frontend/src/routes/ProcessModelShow.tsx b/spiffworkflow-frontend/src/routes/ProcessModelShow.tsx
index fd9f7b85..4112c6e8 100644
--- a/spiffworkflow-frontend/src/routes/ProcessModelShow.tsx
+++ b/spiffworkflow-frontend/src/routes/ProcessModelShow.tsx
@@ -417,13 +417,15 @@ export default function ProcessModelShow() {
   };
 
   const checkDuplicateFile = (event: any) => {
-    if (processModel && processModel.files.length > 0) {
+    if (processModel) {
       let foundExistingFile = false;
-      processModel.files.forEach((file) => {
-        if (file.name === filesToUpload[0].name) {
-          foundExistingFile = true;
-        }
-      });
+      if (processModel.files.length > 0) {
+        processModel.files.forEach((file) => {
+          if (file.name === filesToUpload[0].name) {
+            foundExistingFile = true;
+          }
+        });
+      }
       if (foundExistingFile) {
         displayOverwriteConfirmation(filesToUpload[0].name);
         setFileUploadEvent(event);
@@ -431,12 +433,11 @@ export default function ProcessModelShow() {
         doFileUpload(event);
       }
     }
+    return null;
   };
 
   const handleFileUpload = (event: any) => {
-    if (processModel) {
-      checkDuplicateFile(event);
-    }
+    checkDuplicateFile(event);
     setShowFileUploadModal(false);
   };
 
@@ -473,9 +474,6 @@ export default function ProcessModelShow() {
   };
 
   const processModelFilesSection = () => {
-    if (!processModel) {
-      return null;
-    }
     return (
       <Grid
         condensed