Rail commuters suffered cancellations and delays on the first weekday of the new winter timetable.
Staff shortages, signalling problems, a landslip and ongoing industrial action were among the issues affecting the network on Monday morning.
Some early-morning trains operated by Northern Rail were cancelled due to a shortage of drivers.
The operator's website listed the issue as affecting a number of services, including between Blackpool North and Manchester Airport, Leeds to York and Sheffield, and Darlington to Saltburn.
As of 8am on Monday, the Transpennine Express had 24 cancellations listed for throughout the day due to a shortage of crew or train faults.
Affected services included those linking Manchester Airport with Edinburgh and Newcastle, and trains from Liverpool Lime Street to Scarborough.
Passengers on Great Western Railway were being warned to expect cancellations, delays and fewer trains between Reading and London Paddington due to a fault with the signalling system at Maidenhead.
Due to strike action by the RMT union, travellers on South Western Railway (SWR) have been warned of fewer trains, earlier finishes and some replacement buses throughout December.
Services are expected to be affected every day until January 2.
Industry groups had previously promised more services, shorter journeys and new routes becoming possible across the country under the new timetable.
RDG said the industry had put "years of work into drafting, consulting and planning" for the changes.
But teething problems were evident when the new timetable came into effect on Sunday, with Great Western Railway and Transport for Wales reporting a slew of cancellations and delays.
Train timetables are changed twice a year, in May and December.
The infamous botched change of May 2018 led to chaos, and passenger watchdog Transport Focus said travellers would be hoping for a smoother introduction with the latest changes.