This is overly dense and could do with editing but is pretty interesting imo. Here’s my attempt at summary:

• NATS gets the flightplan in ICAO format
• they need to extract just the UK part of that flight plan
• they convert the ICAO flight-plan to ADEXP format, which contains additional waypoints
• they find the UK section of the ADEXP
• they now need to convert back to ICAO
• they try to match the start and end of the UK ADEXP to ICAO
• duplicate waypoint names exist! The end of the ADEXP route gets wrongly matched with the start of the ICAO route (cos they have the same name)
• the software recognises this doesn’t make sense, but instead of rejecting this flight plan shuts the entire system down
• the backup system comes online, and reprocesses the same data, hits the same bug, and shuts down as well

Basically it sounds like an utter fucking shit show for something so safety critical, and the report from NATS unsurprisingly but disappointingly tries to spin it as positively as possible