Apple Inc.'s entry into Japanese digital payments is off to a rough start as system trouble prevents commuters from charging their passes.

East Japan Railway Co. said users are experiencing difficulties connecting to the Mobile Suica contactless payment system, after the rail operator servicing Tokyo metropolitan area began accepting Apple Pay on Tuesday. The trouble started shortly after 9am in Tokyo, according to Apple's page tracking status of various services.

Apple is seeking a foothold in a market where people still prefer paying with cash despite years of using rail passes that double as electronic money cards. The Cupertino, California-based company's new iPhone 7 includes support for the FeliCa standard, a tap-to-pay technology used in cards such as the Suica and Pasmo rail passes widely accepted in Tokyo and Osaka. Winning over Japanese commuters could foster growth in e-money usage through Apple Pay and entice more people to buy its phones.

JR East said problems were due to the large number of attempts to access the service. Apple Pay and Mobile Suica were the top trending Twitter topics in Tokyo. Users took to social media to express their frustration.

"This makes me worried about system stability going forward," @ltdexp_1002M posted on Twitter. "Seriously? This may be the first service outage ever for Suica?" said another user posting under @taturou.