A few years back, NATS went down because a flight plan waypoint confused the system and it crashed. They had to manually find the problematic flight plan, remove it and start the whole system back up.
Considering the last issue they encountered, it looks like in more than one place, there is no error catching and graceful resolution for those errors.
I would assume a system of such importance to handle issues without hiccups and alert the operators of what did not work. Like “this input caused this problem”, not just crash.
Back in 2023 when the previous issue happened, it didn't actually "crash", it detected what it perceived as an inconsistency (which was due to invalid waypoint logic for waypoint codes in multiple countries) and put itself in "maintenance mode".
My point was that it should not have happenned in the first place. It should have just rejected the flight plan, sent a notice to whatever coordination center would have been in charge of the flight and kept running.
The fact that it entered in maintenance mode still ruined a lot of people’s days.
I don’t think any flight crew or passenger cared about semantics back then.