Compatibility Issue Running Isaac Lab 1.4 Project on Isaac Sim 4.5: ModuleNotFoundError for omni.isaac.kit

Omniverse Isaac Sim
1

Filled Issue Template

​Note: For any Isaac Lab topics, please submit your topic to its GitHub repo (IsaacLab) following Contributing Guidelines.

Isaac Sim Version

4.5.0
4.2.0
4.1.0
4.0.0
2023.1.1
2023.1.0-hotfix.1
Other (please specify):

Operating System

Ubuntu 22.04
Ubuntu 20.04
Windows 11
Windows 10
Other (please specify):

GPU Information

  • Model: (e.g., RTX 2080Ti)
  • Driver Version: (e.g., 535.247.01)

Topic Description

Detailed Description

​Problem: Attempting to run a project built for Isaac Lab 1.4 on a system with Isaac Sim 4.5.0 and Isaac Lab 2.2. After compiling Isaac Lab 1.4 from source, executing create_empty.py fails due to missing omni.isaac.kit. This module was deprecated in Isaac Sim 4.x.

​Expected: The legacy project should initialize without import errors.
​Actual: Critical ModuleNotFoundError halts execution.

Steps to Reproduce

  1. Install Isaac Sim 4.5.0
  2. Clone Isaac Lab 1.4:
git clone -b v1.4.0 https://github.com/isaac-sim/IsaacLab.git
  1. Compile extensions:
cd IsaacLab  
./install.sh
  1. Run legacy tutorial:
python source/standalone/tutorials/00_sim/create_empty.py

Error Messages

Traceback (most recent call last):  
  File ".../create_empty.py", line 20, in <module>  
    from omni.isaac.lab.app import AppLauncher  
  File ".../app_launcher.py", line 26, in <module>  
    from omni.isaac.kit import SimulationApp  
ModuleNotFoundError: No module named 'omni.isaac.kit'

Screenshots or Videos

(Optional: Attach console output screenshots)

Additional Information

What I’ve Tried

  1. ​Symbolic linking: Created symlink _isaac_sim → /isaac-sim
  2. ​Path injection: Added Isaac Sim’s kit to sys.path
  3. ​Code patches: Attempted to replace omni.isaac.kit with isaacsim.simulation_app (but will occur another more complicated error)

​Open Questions:

I plan to install an older Isaac Sim version compatible with Isaac Lab 1.4. Is this feasible? If so:
​1、Which specific Isaac Sim version​ should I install?
2、Are there known ​version constraints​ or best practices for this downgrade?
3、Perhaps you could provide me with an official tool/tutorial for code migration

2

Please try from isaacsim import SimulationApp

In Isaac sim 4.5, we provide a lot of standalone examples, you can refer to the examples for importing SimulationApp. The standalone examples are usually under where you installed Isaac Sim 4.5.

For Isaac Sim 4.5 APIs, please refer to Isaac Sim: Extensions API — Isaac Sim