The majority of customers would still have been able to watch sport yesterday's on their computers via Sky's website, Fellet said.
However, the Herald is aware of some customers who could not log onto the website either.
Yesterday's fault is the second big failure within a year for SkyGo, the other being its outage during July's historic All Blacks test against Samoa in Apia.
Fellet said the technology which checks that someone logging into the app was a subscriber failed yesterday.
The company which provides the technology for the SkyGo service was still unable to say why the fault happened, he said.
Problems with the app were resolved around 11 o'clock last night.
Asked if he was confident SkyGo was robust, Fellet said: "I'm never confident, trust me, dealing with technology, but always optimistic."