In my current v4.26 game I got fed up with losing missiles when the launching ship is destroyed and decided to try and give the missiles an onboard guidance capability. So I added a thermal sensor to the missile on its next upgrade. So far so good, in the next engagement some of the launching ships were destroyed and the missiles continued on. The only problem was when they reached the target and I got the following error message:
Error in check for missile targets
Error 422 was generated by Aurora
object required
It did this for each missile and I had 720+ missiles in flight of which about 200+ had lost their guidance. It took over 200 mouse clicks to clear the error message when it was ok again until more missiles closed on target when the exercise was repeated

. However, to add insult to injury I have only breached the armour on one enemy ship so far, the engagement continues after my fingers recover

.
Regards