# Example errors of IsaacSim 2021.2 ver

**URL:** <https://forums.developer.nvidia.com/t/example-errors-of-isaacsim-2021-2-ver/197454>\
**Category:** Isaac Sim\
**Created:** [December 8, 2021, 9:40am UTC](https://forums.developer.nvidia.com/t/example-errors-of-isaacsim-2021-2-ver/197454 "2021-12-08T09:40:40Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![swimpark](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@swimpark](https://forums.developer.nvidia.com/u/swimpark)\
**Post date:** [December 8, 2021, 9:40am UTC](https://forums.developer.nvidia.com/t/example-errors-of-isaacsim-2021-2-ver/197454/1 "2021-12-08T09:40:40Z")

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Hi.

I am trying to apply RMPflow to my robot using new version of IsaacSim(2021.2).

First, I wanna check the related example, ‘Isaac Examples/Manipulation/Follow Target’, but I cannot open the file with this error when I click ‘World Controls/Load’.

> 2021-12-08 09:36:54 [Error] [asyncio] [/home/idim/.local/share/ov/pkg/isaac\_sim-2021.2.0/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/idim/.local/share/ov/pkg/isaac\_sim-2021.2.0/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/idim/.local/share/ov/pkg/isaac\_sim-2021.2.0/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/idim/.local/share/ov/pkg/isaac\_sim-2021.2.0/exts/omni.isaac.examples/omni/isaac/examples/base\_sample/base\_sample.py”, line 48, in load\_world\_async  
> await self.world.reset\_async()  
> File “/home/idim/.local/share/ov/pkg/isaac\_sim-2021.2.0/exts/omni.isaac.core/omni/isaac/core/world/world.py”, line 196, in reset\_async  
> task.set\_up\_scene(self.scene)  
> File “/home/idim/.local/share/ov/pkg/isaac\_sim-2021.2.0/exts/omni.isaac.core/omni/isaac/core/tasks/stacking.py”, line 66, in set\_up\_scene  
> scene.add\_default\_ground\_plane()  
> File “/home/idim/.local/share/ov/pkg/isaac\_sim-2021.2.0/exts/omni.isaac.core/omni/isaac/core/scenes/scene.py”, line 162, in add\_default\_ground\_plane  
> restitution=restitution,  
> File “/home/idim/.local/share/ov/pkg/isaac\_sim-2021.2.0/exts/omni.isaac.core/omni/isaac/core/objects/ground\_plane.py”, line 77, in **init**  
> collision=True,  
> File “/home/idim/.local/share/ov/pkg/isaac\_sim-2021.2.0/exts/omni.isaac.core/omni/isaac/core/prims/geometry\_prim.py”, line 57, in **init**  
> prim = get\_prim\_at\_path(prim\_path)  
> File “/home/idim/.local/share/ov/pkg/isaac\_sim-2021.2.0/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)

I didn’t change any files or codes, and do not know what it doesn’t work.

What can I do ?

Thank you.

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<div class="post-metadata">

**Author:** ![Hammad\_M](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/hammad_m/32/14047_2.png) [@Hammad\_M](https://forums.developer.nvidia.com/u/Hammad_M)\
**Post date:** [December 8, 2021, 5:38pm UTC](https://forums.developer.nvidia.com/t/example-errors-of-isaacsim-2021-2-ver/197454/2 "2021-12-08T17:38:00Z")

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@swimpark can you try opening the following file?  
`omniverse://localhost/Isaac/Environments/Grid/default_environment.usd`

If this doesn’t exist I would recommend deleting the `/Isaac` folder on your localhost nucleus server and then following this to download the assets again.  
[https://docs.omniverse.nvidia.com/app\_isaacsim/app\_isaacsim/install\_basic.html#isaac-sim-first-run](https://docs.omniverse.nvidia.com/app_isaacsim/app_isaacsim/install_basic.html#isaac-sim-first-run)

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<div class="post-metadata">

**Author:** ![system](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/system/32/68080_2.png) [@system](https://forums.developer.nvidia.com/u/system)\
**Post date:** [April 5, 2024, 3:36pm UTC](https://forums.developer.nvidia.com/t/example-errors-of-isaacsim-2021-2-ver/197454/3 "2024-04-05T15:36:45Z")

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