Trains were delayed on the Expo and Millennium lines, between Commercial Drive and Waterfront, since at least 6:50 a.m. PT.
TransLink tweeted at 8:37 a.m. PT that a "timed out" train was causing problems at the downtown terminus, and that trains would have to use just one side of the station's platform.
TransLink attributed the problem to a switch problem at Waterfront Station.
Minutes later, TransLink tweeted that delays on the system would continue to affect the morning rush.
"Sorry for any inconvenience and thank you for your patience," it said.
Did this morning's switch problem affect your commute? Tell CBC News in the comments below, or by tweeting @cbcnewsbc.