Westpac has experienced its second major systems outage since debuting its new online and mobile banking platform just over a year ago, after an overnight system upgrade downed online banking for most of Sunday.
Scheduled maintenance on Westpac's Live platform had been due to run from 11:00pm January 17th to 8:00am the following morning, but users found mobile and online banking remained inaccessible as they woke up on Sunday.
Westpac later revised the maintenance period to 11:00am, but systems issues continued, with no estimated time of restoration.
Customers were advised to use phone banking instead to access their accounts.
"Westpac Live is unavailable due to an extended planned outage and will be restored as soon as possible. Apologies for any inconvenience."
The online and mobile banking platform appeared to be restored at around 5:30pm.
The systems issues follow a nine-hour outage to the Westpac Live platform at around the same time last year.
Westpac launched the Fiserv-based Live platform in November 2013. It completed the rollout to its 2.7 million personal banking customers late last year and is now working to shift its 800,000 business banking customers over by the middle of 2015.
Update 19/1/15: A Westpac spokesperson said the outage had not been a result of issues with the upgrade, rather the maintenance had taken longer than anticipated.