It doesn't look like Office 365 will be up for all 365 days of this particular year.

The cloud version of Microsoft Office is offline for many users in what seems like a worldwide issue after a network update went haywire.

The company is currently in the process of unwinding the update, which seems to be resolving the issue after close to three hours of dead air.

"While cloud computing is, generally speaking, more reliable than sticking stuff on a server in a dusty brook cupboard, the cloud isn't infallible," internet computing expert Ben Kepes tells the Herald.

"Customers need to have a Plan B for when things go bad. That said, cloud vendors are very good at learning from their mistakes and, unlike traditional software where outages where opaque, I fully expect a detailed post-mortem about this outage and some clear direction as to why it won't happen again.

"Every cloud vendor has outages and while some low level salespeople inside Google and Amazon might seek to score a few points against Microsoft because of this outage, any tech industry person worth their salt realises that 'there but for the grace of God go they'."

As of 4pm NZT, large parts of the service was still down and Microsoft's Office365 Twitter account was still fielding a barrage of queries from users (whom it all directed to a status page).

The company's latest update, some two-and-a-half hours into the outage, hints that the clouds may be beginning to clear.

"We've identified that a recent networking update may have caused user traffic coming from the internet to fail intermittently before reaching Microsoft 365 services. We've reverted this update and are seeing some initial signs of mitigation. We're continuing to validate the cause of the problem while we monitor the environment for service recovery," it says.

At 2.13pm NZT, Microsoft posted a bulletin saying, "We've identified a problem that may be preventing customers from accessing the Microsoft 365 admin center and multiple services. We're working to restore access to the admin center, and we'll provide more information when we've isolated the root cause."

Administrative functions are inaccessible for many users in the US, Australia, NZ and elsewhere and functions including Teams, SharePoint, OneDrive, Skype, Yammer and Outlook 365 are offline.