fix #1567

Former-commit-id: 8c01ffe8d277d49a413571e0669f460c8d0802bf

src/llmtuner/train/ppo/trainer.py

@@ -74,10 +74,13 @@ class CustomPPOTrainer(PPOTrainer, Trainer):
             else:
                 self.reward_model = self.accelerator.prepare_model(self.reward_model, evaluation_mode=True)
 
-    def ppo_train(self) -> None:
+    def ppo_train(self, resume_from_checkpoint: Optional[str] = None) -> None:
         r"""
         Implements training loop for the PPO stage, like _inner_training_loop() in Huggingface's Trainer.
         """
+        if resume_from_checkpoint is not None:
+            raise ValueError("`resume_from_checkpoint` will be supported in the future version.")
+
         total_train_batch_size = (
             self.args.per_device_train_batch_size * self.args.gradient_accumulation_steps * self.args.world_size
         )