An error message greeted some users of Nets' mobile wallet yesterday - the day of the app's launch.
They had downloaded the NetsPay app but could not enter their banking PINs to complete the registration. Instead, they got this error message: "Error 29 - 993. Transaction unsuccessful. Please try again."
The problem was resolved only at 3.30pm.
Electronic payment stalwart Nets said the app attracted more than 6,400 downloads yesterday.
"As an avid supporter of the cashless payment drive in Singapore, I am very disappointed to see the failure of the NetsPay app at the first step of onboarding customers. Why can't we get this right?" said lawyer Rajesh Sreenivasan, 48, who encountered the error message.
Mr Andrew Loh, another frustrated user, said on Nets' Facebook page: "Bad launch. Unable to set up."
The users of seven million ATM cards issued by DBS Bank and POSB are supposed to be the first to have access to the NetsPay app.
The ATM cards of five other banks - OCBC Bank, United Overseas Bank (UOB), HSBC, Maybank and Standard Chartered Bank - will be accepted in the coming weeks.
A spokesman for DBSapologised for the inconvenience, and said some DBS and POSB customers experienced difficulties caused by "an issue with our card provisioning service".
NetsPay is meant to pave the way for millions of ATM card users here to make Nets payments with just their phones.
The app lets users digitise their ATM cards, so payments can be debited directly from their bank accounts by them tapping their cellphones on a contactless payment reader or by scanning a QR code.
The app's introduction was seen by observers as a move towards setting up the unified cashless payment system that Prime Minister Lee Hsien Loong spoke of at this year's National Day Rally.
His remarks on Aug 20 fired the starting gun for a race in which e-payment firms battle to be the one to unite fragmented platforms and reach all strata of society, including hawkers and heartland shops, where cash is king.
Nets chief executive Jeffrey Goh had called NetsPay "the payment app that can".
"It effectively solves Singapore's cashless conundrum - having one wallet that is accepted everywhere," he said on Thursday.
Nets is owned by DBS, OCBC and UOB. About one-third of Nets' 100,000 acceptance points islandwide - including at some Cold Storage and FairPrice supermarket outlets - have been upgraded with contactless functions and QR code features to accept NetsPay.
Android phone users can scan a QR code or tap their phones on contactless payment readers to make payments. iPhone users can only scan a QR code.