The issue reportedly involved documentation from New Zealand's Civil Aviation Authority, which had been included with Air New Zealand's application to enable the plane to make a landing in China. "As you were advised onboard, the aircraft operating your flight did not have regulatory approval to land in China and was required to return to Auckland", the message from the airline said.
Chinese Foreign Ministry spokesman Hua Chunying blamed the flight's temporary deployment hiccup as a reason for the denial of authorisation to land in China, citing news reports she read online.
It is understood Flight NZ289, carrying about 270 passengers, was operated by a newer Boeing 787-9 aircraft not yet been entered in a database of planes allowed to land in China. Calls to the civil aviation administration were not answered.
Air New Zealand flies direct from Auckland to Shanghai six times a week.
"It gets into the political situation and the way the different governments recognise or don't recognise states, and I would think Air New Zealand would be guided very much by what the New Zealand government position is ... therefore look at it in context of the New Zealand government's relationship with China". The Taiwanese government responded by condemning the letter and calling the action as "crude attempts to coerce foreign airlines to "downgrade Taiwan's status".
Ardern is left trotting out the line that this is a scheduling issue, and the only thing keeping her from an official visit is scheduling clashes.
Relations between China and New Zealand have been strained in recent months after New Zealand's spy agency in November halted mobile company Spark from using Huawei equipment in its planned 5G upgrade.
That followed a defense policy statement in July, in which New Zealand said China's rising influence in the South Pacific could undermine regional stability, and alluded to tension in the disputed South China Sea, sparking complaint from China.
In February 2018, the Chinese government had instructed airlines to review their website references, and remove any material that identified Taiwan, Macau and Hong Kong as independent regions - a demand that was reiterated to 44 worldwide carriers in a letter.