A system glitch on Tuesday partially disabled the functions of Japanese smartphone apps designed to pay for train rides and settle other payments.
East Japan Railway says it has been notified by Apple that network problems in the iPhone operating system, iOS, may be the cause.
JR East and other railway companies reported problems with Mobile Suica and Mobile Pasmo apps.
They say users were unable to recharge the apps or purchase commuter passes and first class seats.
Some passengers were blocked from exiting ticket gates, because their apps had run out of credit.
The railway companies say the Japanese payment apps could still be recharged with cash at vending machines installed at stations.