A "rescue train" was sent to help passengers from a Caledonian Sleeper service which broke down in a remote area of the Highlands.
The overnight service to London Euston was cancelled due to a power failure shortly after it left Fort William on Friday.
Caledonian Sleeper "sincerely apologised" and said Sunday night's services would start from Edinburgh.
It is the latest in a series of problems facing the rail firm.
Since launching its new £150m fleet to great fanfare in April, passengers travelling between the Central Belt and London have faced disruption and cancellations.
And last week it emerged that the launch of the new trains on the Highland line would be delayed - so the carriages could support the Lowland service.
Transport Scotland said the delay was "unacceptable" and penalties would be applied.
The latest problem happened on the overnight service from Fort William when the train failed between Corrour and Tulloch.
In a series of post on Twitter, Caledonian Sleeper told passengers "a rescue train is on its way" but they advised it would be badly delayed.
Later they said they were "currently working" on a plan to get travellers to Glasgow Central station and then to London.
Fort William to Euston Service has been cancelled due to a loco failure between Corrour and Tulloch a rescue train is on its way but please be advised this service will be heavily delayed Caledonian Sleeper apologise for this disruption and for the inconvenience caused— Caledonian Sleeper (@CalSleeper) June 28, 2019
Service Update - Glasgow to London Euston: We apologise for the cancellation of Friday night's service, which was due to a power issue. Ticket acceptance is in place on the 04:14 Virgin Trains service from Glasgow Central to London Euston on Saturday morning.— Caledonian Sleeper (@CalSleeper) June 29, 2019
Caledonian Sleeper sincerely apologise for last nights cancellations and disruptions to service.— Caledonian Sleeper (@CalSleeper) June 29, 2019
We are currently working on a plan to get the Fort William guests to Glasgow Central Station then onward to London.
We will update later on plans for tomorrow nights services.
It has led to knock-on problems with the Sunday night services between Fort William and London Euston.
Passengers travelling north have been advised that they will be taken from London to Dumbarton Central by road and their Sleeper service will start at Edinburgh Waverley.
And those heading south have been advised that they will be taken from Fort William to Waverley by road.