fixed

model_training_nnn_tpu/rnn_model_tf.py

@@ -832,7 +832,16 @@ def create_tpu_strategy():
             print("   Common variables: COLAB_TPU_ADDR, TPU_NAME, TPU_WORKER_ID")
 
         print("🔄 Falling back to default strategy (CPU/GPU)")
-        return tf.distribute.get_strategy()
+        fallback_strategy = tf.distribute.get_strategy()
+        print(f"🎯 Fallback strategy created: {type(fallback_strategy).__name__}")
+        print(f"📊 Fallback strategy replicas: {fallback_strategy.num_replicas_in_sync}")
+
+        # Ensure we never return None
+        if fallback_strategy is None:
+            print("⚠️  Warning: Default strategy is None, creating OneDeviceStrategy")
+            fallback_strategy = tf.distribute.OneDeviceStrategy("/CPU:0")
+
+        return fallback_strategy
 
 
 def build_model_for_tpu(config):