The glitch was resolved at the ProRail Rail Director’s Traffic Control Center in Rotterdam around midnight from Sunday to Monday. The outage shut down trains in the area for several hours on Sunday evening. NS has announced that it will deploy as many additional trains as possible during the night to be able to take all stranded travelers home after all.

Due to the malfunction, ProRail has not been able to see where the trains are in the Rotterdam area for a while. That was unsafe. “The glitch at the Rotterdam traffic control center appeared on Sunday evening around 8:30 p.m. on one of the computers,” ProRail wrote online.

The computer system has a backup in case such a failure occurs. But that backup system didn’t work properly on Sunday. ProRail: “Extensive research is being done on why this is, but it appears to be due to a software bug. As a result, many systems are no longer working.”

A NS spokesperson said the disruption affected all trains to and from Rotterdam and Dordrecht. Also, trains on the high-speed line between Amsterdam Central and Breda were not running.

ProRail advises travelers to consult a travel planner for the latest travel information.