I would not be much bothered, since I have huge income and a few militias would not be a big deal to retrain. But:
1) They seem to happen to settlements just a few turns before they can be upgraded.
2) They happen to settelements where you have high rank characters, who may die from this crap.
3) They happen to settlements where you have some elite units and they will have to go far behind to your main cities to replenish.
4) At around turn 90, every turn there are 1-2 settlements afflicted. At round 98, I have 31 cities...what will happen when I will have 100???

I usually reload before the turn, do some things more like infiltrate a city etc to change the RNG...But this is getting tiresome.
Any way to completely remove that annoyance?