In the Paradox Launcher, use the "Clear User Directory" button. This removes broken cache files, such as the naval cache, which frequently cause loading failures.
The MD team updated the province ID limit beyond the base game's safe threshold. The Fix: hoi4 millennium dawn crash fix 2021
— End of report.
Run with elevated resources / reduce memory pressure In the Paradox Launcher, use the "Clear User
Turn off all other mods (even graphical ones like "Player Led Peace Conferences" or "Colored Buttons") to see if the crash persists. In the Paradox Launcher