Dependency Error with Gymnasium 1.0 for Mujoco Environments

[Shawnzty]

I encountered an error while following the Reinforcement Learning (PPO) with TorchRL tutorial when trying to instantiate the "InvertedDoublePendulum-v4" environment. The error message was:

ImportError: RuntimeError: TorchRL does not support gymnasium 1.0 or later versions due to incompatible
changes in the Gym API.

I solved this error by downgrade Gymnasium to the version earlier than v1.0 and then install the mujoco.

pip uninstall gymnasium
pip install gymnasium==0.27.1
pip install "gymnasium[mujoco]"