How to reproduce:
1. Open the “IN_67365” project
2. In the Project window search for the “Player” prefab and open it
3. In the Hierarchy expand the “Player” GameObject and select “Hips“ GameObject
4. Enter and exit the Play Mode
5. In the Inspector enable “ArticulationBody/Immovable“
Expected result: Player doesn’t crash
Actual result: Player crashes
Reproducible with: 2021.3.34f1, 2022.3.19f1, 2023.2.8f1, 2023.3.0a16
Not reproducible with: 2023.3.0b5
Fixed in: 2023.3.0a17
Reproducible on: Windows 10 Pro, macOS Ventura 13.5.2 (M1)
Not reproducible on: No other environments tested
Note: 4 and 5 steps could be reproduced differently so if the issue doesn’t reproduce try entering the Play Mode, toggling the Immovable setting the the Inspector, exiting the Play Mode and repeating this a couple of times
First lines of the Stack trace: