diff --git a/skyrl/backends/skyrl_train/inference_engines/vllm/vllm_engine.py b/skyrl/backends/skyrl_train/inference_engines/vllm/vllm_engine.py
index 3bebbd8655..ef5e3902b9 100644
--- a/skyrl/backends/skyrl_train/inference_engines/vllm/vllm_engine.py
+++ b/skyrl/backends/skyrl_train/inference_engines/vllm/vllm_engine.py
@@ -170,6 +170,18 @@ def _get_engine(self):
         """Get the underlying engine for RPC calls."""
         return self.llm.engine if hasattr(self.llm, "engine") else self.llm
 
+    @staticmethod
+    def _get_unfinished_request_ids(output_processor) -> list:
+        """Get unfinished request IDs suitable for abort/abort_request calls.
+
+        In vllm 0.16.0+, request_states is keyed by internal IDs (with a random suffix),
+        while abort() expects external IDs by default. We use external_req_ids when
+        available and fall back to request_states keys for older vllm versions.
+        """
+        if hasattr(output_processor, "external_req_ids"):
+            return list(output_processor.external_req_ids.keys())
+        return list(output_processor.request_states.keys())
+
     def reset_prefix_cache(self):
         """Reset the prefix cache. Subclasses override for async version."""
         return self.llm.llm_engine.reset_prefix_cache()
@@ -245,7 +257,7 @@ async def sleep(self, *args: Any, **kwargs: Any):
                 "generation should be done before sleep() is called. Check for potential failures or "
                 "dangling requests in your Generator/Env. Aborting all unfinished requests."
             )
-            unfinished_request_ids = list(output_processor.request_states.keys())
+            unfinished_request_ids = self._get_unfinished_request_ids(output_processor)
             await asyncio.to_thread(engine.abort_request, unfinished_request_ids)
 
         level = 1 if self._is_lora else kwargs.get("level", 2)
@@ -457,7 +469,7 @@ async def sleep(self, *args: Any, **kwargs: Any):
                 "generation should be done before sleep() is called. Check for potential failures or "
                 "dangling requests in your Generator/Env. Aborting all unfinished requests."
             )
-            unfinished_request_ids = list(output_processor.request_states.keys())
+            unfinished_request_ids = self._get_unfinished_request_ids(output_processor)
             await engine.abort(unfinished_request_ids)
 
         # TODO(team): remove once vllm fixes this
@@ -608,8 +620,7 @@ async def abort_generation(self) -> None:
         already-generated tokens with a stop_reason of "abort".
         """
         engine = self._get_engine()
-        # Collect all request IDs currently tracked by the scheduler/output processor
-        unfinished_request_ids = list(engine.output_processor.request_states.keys())
+        unfinished_request_ids = self._get_unfinished_request_ids(engine.output_processor)
         if unfinished_request_ids:
             await engine.abort(unfinished_request_ids)
         await engine.reset_prefix_cache()  # avoid KV-cache pollution