isaaclab.sh -p fails with "No module named isaaclab" on binary install (Isaac Sim 5.1.0)

[Ohaginia]

Environment

• Isaac Sim: 5.1.0-rc.19 (binary install, symlinked at IsaacLab/_isaac_sim)
• Isaac Lab: Latest main branch (source at IsaacLab/source/isaaclab/)
• OS: Ubuntu 22.04, Linux 6.8.0
• Python: Kit-bundled Python 3.11 (_isaac_sim/kit/python/bin/python3.11)
• PyTorch: 2.7.0+cu128

Problem

Running any script with isaaclab.sh -p that imports isaaclab fails:

$ isaaclab.sh -p my_script.py --headless
[INFO] Using python from: /home/user/IsaacLab/_isaac_sim/python.sh
ModuleNotFoundError: No module named 'isaaclab'

However, isaacsim imports fine:

>>> import isaacsim  # OK - found at _isaac_sim/python_packages/isaacsim/
>>> import isaaclab   # FAILS

pip list in the kit Python shows 266 packages (torch, ROS2 msgs, etc.) but no isaaclab* packages at all.

The source/isaaclab/setup.py exists on disk but has never been installed into the kit Python environment.

What I tried

1. unset VIRTUAL_ENV && isaaclab.sh -p my_script.py → same error
2. Direct _isaac_sim/python.sh my_script.py → same error
3. Confirmed CONDA_PREFIX is not set

Question

Is isaaclab.sh --install (i.e., isaaclab.sh -i) a required setup step before isaaclab.sh -p can work with a binary Isaac Sim install? The installation docs mention running the installer, but I want to confirm:

1. Is isaaclab.sh -i the correct fix for this?
2. Are there any known issues with isaaclab.sh -i on Isaac Sim 5.1.0-rc.19?
3. Does -i modify the kit Python's site-packages in-place, or does it require a venv/conda env?

Any guidance appreciated. Thanks!

[PrithwishDas101]

Yes — based on what you've described, the missing installation step is the first thing to fix.

Having "source/isaaclab/setup.py" on disk doesn't make the "isaaclab" package importable. You need to install the Isaac Lab packages into the Python environment you're using to run your scripts.

From the root of your IsaacLab checkout, run:

./isaaclab.sh --install

Then verify the installation using the same Python environment:

./isaaclab.sh -p -c "import isaaclab; print(isaaclab.file)"

If you're on Windows, use "isaaclab.bat --install" and the corresponding "isaaclab.bat" Python command.

The official binary-installation guide documents this installation step:
https://isaac-sim.github.io/IsaacLab/main/source/setup/installation/binaries_installation.html

If the import still fails after installation, check that you're running the script with the same environment that the installer used.