Commuters were left confused and frustrated after several Auckland Transport services, including train and bus timetables, went offline for almost 12 hours.
The outage affected live departure boards at bus stops and train stations, as well as on Auckland Transport's website and mobile app.
A spokesperson said the outage began shortly before midnight.
Commuters told RNZ they had no idea when, or if, the next train or bus would arrive.
"It's surprising how relevant these signs are to you managing your day," said an Aucklander who buses to work every morning. "I'll just get an Uber to the office, which kind of defeats the purpose of having a bus network."
Faulty timetables were a "regular occurrence," he said. "It's quite an inconvenience. It's just part of the logistics of getting to and from work, and a reliable bus service which we'd all love to have - but sometimes its just not there."
Timetables at Auckland's Britomart Station were also affected, and one passenger worried there had been a crash.
"I'm worried, just in case there's been an accident," she said. "I need to know what's going on... I'm sitting here thinking: will I be able to go [to work] or not?"
A visitor from Christchurch said he felt lost. "I didn't know which platform to go on because I only come up to Auckland every few months," he said.
Auckland Transport said the outage was caused by major power surge at a Microsoft Azure facility in Australia.
Commuters were surprised the service was so fragile. "It's pretty frustrating because the app isn't working at the same time," one said. "I thought there'd be a back-up plan or something."
"This shows how much we rely on the internet, apps and all of that. We have to have an alternative somehow," said another.
Service was restored just before midday.