[2021] Fail to Save the Game !

My guess is you have an outdated mod that's messing with things. Check your mods against this list of known broken and incompatible mods and get replacements where available.

https://docs.google.com/spreadsheets/d/1mVFkj_7ij4FLzKs2QJaONNmb9Z-SRqUeG6xFGqEX1ew/edit?usp=sharing

Originally posted by Josel: I have the same issue

Please report your issue on the support forum here:
https://forum.paradoxplaza.com/forum/forums/support-bug-reports.879/

This thread is over a year old and we've had two major patches since then. Even if the issue is similar, the cause and solution might be entirely different.