external project with Newton

[gecastro]

Hi there,

I' m new to Isaaclab and I'm currently trying to create an external project and train using newton. My environment is:

• Windows 11
• miniconda (powershell)
• Isaaclab 3.0.0-beta2

I did create the external project and run this without issues:

C:\lab\IsaacLab\isaaclab.bat -p .\scripts\rsl_rl\train.py --task=Template-Task-v0

It runs successfully with a deprecation warking train.py, additionally I'd like to run the training with Newton. Then when I run the command:

C:\lab\IsaacLab\isaaclab.bat train --rl_library rsl_rl --task=Template-Task-v0

I receive the error:

[INFO] Using Python: "C:\miniconda3\envs\lab3\python.exe"
Traceback (most recent call last):
  File "C:\lab\IsaacLab\scripts\reinforcement_learning\train.py", line 37, in <module>
    raise SystemExit(main())
                     ^^^^^^
  File "C:\lab\IsaacLab\scripts\reinforcement_learning\train.py", line 27, in main
    return dispatch_library_entrypoint(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\lab\IsaacLab\scripts\reinforcement_learning\common.py", line 79, in dispatch_library_entrypoint
    module.run(library_args)
  File "C:\lab\IsaacLab\scripts\reinforcement_learning\rsl_rl\train_rsl_rl.py", line 116, in run
    env_cfg, agent_cfg = resolve_task_config(args_cli.task, args_cli.agent)
                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\lab\IsaacLab\source\isaaclab_tasks\isaaclab_tasks\utils\hydra.py", line 463, in resolve_task_config
    env_cfg, agent_cfg, hydra_args = register_task(task, agent_cfg_entry_point)
                                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\lab\IsaacLab\source\isaaclab_tasks\isaaclab_tasks\utils\hydra.py", line 573, in register_task
    env_cfg = load_cfg_from_registry(task_name, "env_cfg_entry_point")
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\lab\IsaacLab\source\isaaclab_tasks\isaaclab_tasks\utils\parse_cfg.py", line 64, in load_cfg_from_registry
    cfg_entry_point = gym.spec(task_name.split(":")[-1]).kwargs.get(entry_point_key)
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\miniconda3\envs\lab3\Lib\site-packages\gymnasium\envs\registration.py", line 1000, in spec
    _check_version_exists(ns, name, version)
  File "C:\miniconda3\envs\lab3\Lib\site-packages\gymnasium\envs\registration.py", line 392, in _check_version_exists
    _check_name_exists(ns, name)
  File "C:\miniconda3\envs\lab3\Lib\site-packages\gymnasium\envs\registration.py", line 369, in _check_name_exists
    raise error.NameNotFound(
gymnasium.error.NameNotFound: Environment `Template-Task` doesn't exist.

I already installed the external project in the miniconda environment. Is this supported or I' m missing something?

[BulletsHo]

Not a bug in your project — you're mixing two separate launch paths that Isaac Lab 3.0 treats differently. What you built with the template generator is an external project, and external projects are still meant to be run through the per-library script directly. The new unified isaaclab.bat train --rl_library ... command currently only resolves tasks that ship inside the Isaac Lab repo itself ("internal" tasks). Your first command was already the correct one — keep using it.

Why the second command fails

The docs page Create new project or task draws an explicit line between the two things the template generator can create:

• External project (what isaaclab.bat --new builds by default — this is what you have) → run tasks with python scripts\<specific-rl-library>\train.py --task=<Task-Name>. That's your first command, and it's the documented, supported way.
• Internal task (a task contributed into the Isaac Lab repo itself) → run tasks with the new unified isaaclab.bat train --rl_library <library> --task=<Task-Name> command.

You can actually see this in your own traceback. Your first command runs scripts\rsl_rl\train.py, the classic per-library script that ships with your generated project. Your second command instead runs Isaac Lab's own scripts\reinforcement_learning\train.py, which dispatches (via dispatch_library_entrypoint in common.py) into a different internal module, scripts\reinforcement_learning\rsl_rl\train_rsl_rl.py, and resolves the task through isaaclab_tasks\utils\hydra.py::register_task → parse_cfg.py::load_cfg_from_registry → gym.spec(...).

That whole chain only ever imports Isaac Lab's built-in isaaclab_tasks package. Template-Task-v0 is registered with Gymnasium by a gym.register(...) call inside your project's tasks/.../__init__.py, and that only runs once something imports it — which your own scripts\rsl_rl\train.py does, but the unified dispatcher never does, since it has no notion your standalone project exists. So by the time gym.spec() goes looking for Template-Task-v0, it was never registered, hence NameNotFound. (The Project Structure page confirms gym.register has to run at least once via import before a task is usable — it's not automatic just because the package is pip-installed.)

So it's not that Newton isn't supported for external projects — the new unified CLI just isn't wired up yet to discover tasks outside the Isaac Lab repo.

What to do

Keep training with the command that already works:

C:\lab\IsaacLab\isaaclab.bat -p .\scripts\rsl_rl\train.py --task=Template-Task-v0

The deprecation warning is generic text baked into every per-library script, pointing everyone at the new unified command. That's correct guidance for first-party/internal tasks, just not (yet) for externally generated ones — safe to ignore it here.

Getting Newton specifically

Switching physics backend isn't about which entry-point script you call — it's a Hydra config-group override, so it works the same on either path:

C:\lab\IsaacLab\isaaclab.bat -p .\scripts\rsl_rl\train.py --task=Template-Task-v0 physics=newton_mjwarp

One thing worth double-checking: the current Newton backend install docs (written against the bleeding-edge develop branch) still list Ubuntu 22.04/24.04 as a requirement for some of the newer solvers. Since you're on release/3.0.0-beta2 on Windows, use the version dropdown on the docs site to jump to your exact release and confirm which Newton solvers are already available to you there vs. still Linux/develop-only — beta2 did expand Newton support significantly over the first 3.0 beta, but not every doc page has a Windows-specific pass yet.

(Isaac Lab 3.0 is still in beta, so this split between external/internal task discovery may well change in a future release — worth keeping an eye on the changelog if the unified command matters to your workflow.)