Errors as running OmnikitHelper.update()


So I was trying to instantiate OmnikiHelper defined here in IsaacSim 2020.2:


then these errors popped out, which seems to render the sim step function failed:

[1.984s] [ext: omni.isaac.manip] startup
2020-11-23 03:18:46 [1,978ms] [Error] [carb.scripting-python.plugin] AttributeError: 'NoneType' object has no attribute 'GetPrimAtPath'

  /home/tad/ISAAC/ISAAC_SIM/_build/linux-x86_64/release/exts/omni.isaac.manip/omni/isaac/manip/scripts/ load_bindings
  /home/tad/ISAAC/ISAAC_SIM/_build/linux-x86_64/release/exts/omni.isaac.manip/omni/isaac/manip/scripts/ on_startup
  /home/tad/ISAAC/ISAAC_SIM/_build/target-deps/kit_sdk_release/_build/linux-x86_64/release/plugins/bindings-python/omni/ext/impl/ _startup_ext
  /home/tad/ISAAC/ISAAC_SIM/_build/target-deps/kit_sdk_release/_build/linux-x86_64/release/plugins/bindings-python/omni/ext/impl/ startup_all_extensions_in_module
  /home/tad/ISAAC/ISAAC_SIM/_build/target-deps/kit_sdk_release/_build/linux-x86_64/release/plugins/bindings-python/omni/ext/impl/ startup_all_extensions_in_module
  /home/tad/ISAAC/ISAAC_SIM/_build/target-deps/kit_sdk_release/_build/linux-x86_64/release(3): <module>

2020-11-23 03:18:46 [1,978ms] [Error] [omni.ext.plugin] [ext: omni.isaac.manip] Failed to process python module extension in '/home/tad/ISAAC/ISAAC_SIM/_build/linux-x86_64/release/exts/omni.isaac.manip/.'.


2020-11-23 02:00:30 [3,142ms] [Error] [omni.kit.ui.python] Model.getValueAs() failed (path: "/persistent/audio/context/streamerFile"). Error: Unable to cast Python instance to C++ type (compile in debug mode for details)
[3.151s] [ext: omni.kit.builtin.profiler] startup
[3.152s] [ext: omni.kit.builtin.provide_feedback_window] startup
[3.152s] [ext: omni.kit.builtin.render_settings_window] startup
[3.160s] [ext: omni.kit.builtin.test_runner] startup
[3.168s] [ext: omni.utils.collect_tool] startup
[3.168s] [ext: omni.utils.movie_capture] startup
[3.168s] [ext: omni.utils.utilities_menu] startup
[3.169s] [ext: omni.assetimport] startup
2020-11-23 02:00:30 [3,320ms] [Error] [omni.ui.python] Unable to cast Python instance to C++ type (compile in debug mode for details)
2020-11-23 02:00:30 [3,426ms] [Error] [omni.stageupdate.python] AttributeError: 'NoneType' object has no attribute 'is_flat'

  ISAAC/ISAAC_SIM/_build/target-deps/kit_sdk_release/_build/linux-x86_64/release/exts/omni.kit.widget.stage-0.1.0/omni/kit/widget/stage/ _on_attach

Would you have any idea about them?


P/s: I specified the parameters as self.update(dt=1/30.0, physics_dt=1/120.0, physics_substeps=4).

Hi Tadinu,

Sorry for my late reply, do you still have this problem?


Hi Liila, @ltorabi

No worries. Yes, If you just happen to have the issue also and could resolve by not by running the script inside the Script Editor, could you please share the info?


Hi @Tadinu
Can you try running the basic time stepping sample from:

Time Stepping Example

Do any errors occur?

The Omnikit helper class can only be executed from a python environment (and not as a script running inside of the script editor).

Hi @Hammad_M,

It looks like has been removed since IsaacSim 2020.2. I could not find it in the source base, but I could run the OmnikitHelper now from this demo ISAAC_SIM/python_samples/syntheticdata/advanced/ I was creating a modified version of it actually, probably I did not run it in Headless mode or happen to change some configurations.
But I just saw these warnings/errors:

simulating physics...
2020-12-03 03:41:15 [27,803ms] [Warning] [carb.tasking.plugin] Counter 0x7fc954096a80 released with 3 waiters; spinning until waiters finish
2020-12-03 03:42:51 [124,010ms] [Error] [omni.syntheticdata.plugin] instanceList is null.


Hi @Tadinu
Sorry!, that was my mistake, we just released a new version of isaac sim 2020.2.2 (alongside isaac sdk 2020.2) today that should have that file.

Warnings and errors that can be ignored are in the known issues section.

instanceList is null.

is an error that can be ignored


Oh I was not aware of the issue list, thanks! Yeah for the release, I will download it now. I just saw the email about the 2020.2 SDK, not think you had the Sim updated as well.
Thanks a lot for the info!

Hi @Hammad_M,
I just found out the cause for the errors above in 2020.1 Sim version. It turns out that using ISAAC_SIM/python_samples/experiences/isaac-sim-python.json the Sim runs without errors.

They only pop up with ISAAC_SIM/_build/linux-x86_64/release/experiences/isaac-sim-headless.json, which I suppose is composed for the Headless running.
And I’m not sure which extensions in enabledBuiltin list or some other settings cause those, but it seems settings->persistent must be false to make it work.

Correct, The Omnikit helper class can only be executed from a python environment and not using any of the other experiences like isaac-sim-headless.

The helper class allows you to set headless vs non-headless directly.

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