TransPennine Express has cancelled more than 100 of its trains in the North of England due to issues with staffing.
The operator says a "significant rostering system issue" means a "high level of unplanned cancellations" are necessary across its network on Wednesday December 21.
By lunchtime on Wednesday TransPennine cancelled 113 trains to and from stations including Berwick, Newcastle, Glasgow, Manchester, Liverpool, York, Hull and Leeds.
Read more: 'Diabolical' cancellations spark calls for North's railways to be nationalised
There are no rail strikes planned on the network on Wednesday. The next industrial action by the RMT is due to start on Christmas Eve.
Kathryn O’Brien, Customer Service and Operations Director for TransPennine Express said: “Due to a significant rostering system issue, today we are experiencing a high level of unplanned cancellations and disruption across our network.
“We know this will have a significant impact on customers travelling with us today and sincerely apologise for any disruption caused.
“We are working hard internally and with our system provider to resolve the situation as soon as possible.
“We are doing all we can to keep customers on the move but while problems persist, we advise customers not to travel and to seek alternative means of transport.”
CrossCountry, LNER, Northern, and Metrolink services are accepting Transpennine tickets for travel on Wednesday. Transpennine tickets for Wednesday can also be used to travel on Thursday December 22 or Friday December 23.
Transpennine Express has come under fire recently for cancelling trains the evening before they are due to depart. If a cancellation is announced the day before departure, it does not have to be included in data used to monitor a rail operator's performance.