City subways snarled during Wednesday’s morning rush, thanks to switch problems at a bustling Harlem station.

The switch problem at the 125th Street-Lexington Avenue station caused service changes and delays on northbound 4, 5 and 6 trains starting around 9 a.m., the MTA said.

Northbound 6 trains were running express from Grand Central-42nd Street to 125th Street and northbound 5 trains were running via the 2 line from Nevins Street to 149th Street-Grand Concourse.

Frustrated straphangers took to Twitter to slam the MTA for the train trouble.

“Delays is an understatement. It’s taking me close to 2 hours to get to work. You guys are TRASH!” Ricki Tannenbaum tweeted.