diff --git a/core/runtime/TRTEngine.cpp b/core/runtime/TRTEngine.cpp
index fb96628ec5..b8b711375e 100644
--- a/core/runtime/TRTEngine.cpp
+++ b/core/runtime/TRTEngine.cpp
@@ -292,6 +292,10 @@ TRTEngine::TRTEngine(
   // engines built outside Torch-TensorRT). User-declared aliases (kind=kUser)
   // are preserved as-is since TRT doesn't know about them.
   this->aliased_io = aliased_io;
+// ICudaEngine::getAliasedInputTensor is not available before TRT 10.15 (e.g. Jetpack
+// L4T builds), where an engine cannot report its aliasing and the build-time map is
+// the only source of truth.
+#if NV_TENSORRT_MAJOR > 10 || (NV_TENSORRT_MAJOR == 10 && NV_TENSORRT_MINOR >= 15)
   for (const auto& out_name : this->out_binding_names) {
     // TRT returns nullptr / empty string for non-aliased outputs; any thrown
     // exception is a real error in the engine state and propagates.
@@ -315,6 +319,7 @@ TRTEngine::TRTEngine(
       it->second = AliasedIOSpec{std::string(aliased_in), AliasKind::kKVCacheUpdate};
     }
   }
+#endif
 
   // Precompute the set of input binding names that are the alias source of some
   // output (for the O(1) per-call membership test) and validate every aliased
diff --git a/py/torch_tensorrt/dynamo/conversion/impl/slice_scatter.py b/py/torch_tensorrt/dynamo/conversion/impl/slice_scatter.py
index c277a4ca6b..579fee0429 100644
--- a/py/torch_tensorrt/dynamo/conversion/impl/slice_scatter.py
+++ b/py/torch_tensorrt/dynamo/conversion/impl/slice_scatter.py
@@ -97,6 +97,16 @@ def emit_kv_cache_update_layer(
         logger.debug("KV cache update: skipped — input is not a direct network input")
         return None
 
+    # add_kv_cache_update and KVCacheMode do not exist before TensorRT 10.15 (e.g.
+    # Jetpack L4T builds). Returning None here takes the caller's existing fallback
+    # instead of raising AttributeError, which reads like a bug in the model.
+    if not hasattr(ctx.net, "add_kv_cache_update") or not hasattr(trt, "KVCacheMode"):
+        logger.debug(
+            "KV cache update: skipped, this TensorRT build has no "
+            "KV-cache update layer"
+        )
+        return None
+
     layer = ctx.net.add_kv_cache_update(
         cache, src, write_indices, trt.KVCacheMode.LINEAR
     )