A computer glitch brought seven subway lines to a halt for more than 90 minutes on Friday evening, stranding rush hour commuters in stuck trains and on sweltering platforms as temperatures in the city climbed to 92 degrees.

Transit officials on Twitter attributed the suspension of service on the 1, 2, 3, 4, 5 and 6 lines and the Times Square-42nd Street shuttles to a “network communications issue” — the same alleged culprit in a similar episode that occurred only 13 days ago on July 6.

The computers that power the subway’s signaling system went on the blink, subways boss Andy Byford said, promising an investigation into what went wrong.

“I absolutely want to get to the bottom of this,” he said.

“I totally understand their frustration,” he said of commuters.

“I’m frustrated about it as well. This should never happened. New Yorkers should be able to rely on the transit system to get them home.”

The “total stoppage” began at 5:50 p.m., MTA spokesman Tim Minton said. Service began to be restored at 7:16 p.m., but residual delays continued.

Without signals, “We did not know exactly where our trains were,” Byford said.

“So for safety reasons, we had to instruct all trains to stop where they were and maintain their positions while we ascertained exactly what was going on,” he explained.

The signaling snafu was solved by simply rebooting the system’s servers, Byford said.

“It was the servers that failed such that the signals could not be seen,” he said.

“The servers were rebooted, and progressively the signal indications came back up,” he said.

“Once we could be certain we … could safely move the trains, we instructed a phased restart and trains began to move,” starting with the express lines, he said.

The stuck trains never lost air conditioning or lighting. Still, straphangers were not happy.

“A systemwide shutdown in July when its ninety degrees outside? And they’re raising the fares again?” asked annoyed commuter Tanya Layne, 30, who was stuck on a downtown 4 train at Atlantic Avenue in Brooklyn.

“I have never been one to freak out. But being stuck in the subway between two trains for over half an hour is doing the trick,” tweeted @CobyMessiah.

“What should we use as a bathroom now that we live down here?” wrote @mrdouglasland.

Additional reporting by Alex Taylor and Laura Italiano