How can I resolve this error?

How can I resolve this error?
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2022-05-02 05:51:14 [Error] [asyncio] [/home/kime/.local/share/ov/pkg/isaac_sim-2021.2.1/kit/python/lib/python3.7/asyncio/base_events.py:1619] Task exception was never retrieved
future: <Task finished coro=<BaseSampleExtension.on_load_world..on_load_world_async() done, defined at /home/kime/.local/share/ov/pkg/isaac_sim-2021.2.1/exts/omni.isaac.examples/omni/isaac/examples/base_sample/base_sample_extension.py:161> exception=ArgumentError('Python argument types in\n None.GetPrimAtPath(Stage, NoneType)\ndid not match C++ signature:\n GetPrimAtPath(pxrInternal_v0_20__pxrReserved::UsdStage {lvalue}, pxrInternal_v0_20__pxrReserved__::SdfPath path)’)>
Traceback (most recent call last):
File “/home/kime/.local/share/ov/pkg/isaac_sim-2021.2.1/exts/omni.isaac.examples/omni/isaac/examples/base_sample/base_sample_extension.py”, line 162, in on_load_world_async
await self.sample.load_world_async()
File “/home/kime/.local/share/ov/pkg/isaac_sim-2021.2.1/exts/omni.isaac.examples/omni/isaac/examples/base_sample/base_sample.py”, line 44, in load_world_async
self.setup_scene()
File “/home/kime/.local/share/ov/pkg/isaac_sim-2021.2.1/exts/omni.isaac.examples/omni/isaac/examples/hello_world/hello_world.py”, line 13, in setup_scene
world.scene.add_default_ground_plane()
File “/home/kime/.local/share/ov/pkg/isaac_sim-2021.2.1/exts/omni.isaac.core/omni/isaac/core/scenes/scene.py”, line 162, in add_default_ground_plane
restitution=restitution,
File “/home/kime/.local/share/ov/pkg/isaac_sim-2021.2.1/exts/omni.isaac.core/omni/isaac/core/objects/ground_plane.py”, line 77, in init
collision=True,
File “/home/kime/.local/share/ov/pkg/isaac_sim-2021.2.1/exts/omni.isaac.core/omni/isaac/core/prims/geometry_prim.py”, line 57, in init
prim = get_prim_at_path(prim_path)
File “/home/kime/.local/share/ov/pkg/isaac_sim-2021.2.1/exts/omni.isaac.core/omni/isaac/core/utils/prims.py”, line 28, in get_prim_at_path
return get_current_stage().GetPrimAtPath(prim_path)
Boost.Python.ArgumentError: Python argument types in
None.GetPrimAtPath(Stage, NoneType)
did not match C++ signature:
GetPrimAtPath(pxrInternal_v0_20__pxrReserved
::UsdStage {lvalue}, pxrInternal_v0_20__pxrReserved__::SdfPath path)

Hi @kqu0585

Could you provide details about how are you calling the world.scene.add_default_ground_plane() method?
For example, a snippet of the code you are testing…