A module that was compiled using NumPy 1.x cannot be run in NumPy 2.0.0 as it may crash.

When you compile a Python module using an older version of NumPy, say 1.x, and then attempt to run it with a newer version like 2.0.0, compatibility issues can arise. This is because the APIs and data structures might have changed between the two versions, leading to possible errors or crashes when the new NumPy expects different behavior or has introduced breaking changes.

Here are some key points to consider:

1. **Dependency updates**: NumPy releases often involve API enhancements and deprecations, which means code written for one version might not work seamlessly with a later one. Functions, arguments, or even the way arrays are handled internally could have changed.

2. **Compatibility layers**: Some libraries like `numpy-stubs` provide compatibility layers that help bridge the gap between old and new NumPy versions, but they might not cover all cases or handle all changes.

3. **Migrating code**: To run your module with NumPy 2.0.0, you may need to update the code to use the new API, remove deprecated calls, or make adjustments for any changes in the underlying data structures.

4. **Checking for version compatibility**: Before running, you can check the NumPy version your module expects by looking at import statements or using `sys.modules['numpy'].__version__`.