The Ministry of Health says it has had no complaints from users of the NZ Covid Tracer app reporting problems with overheating.
An updated app was rolled out a week ago.
A fault message told one user the app had closed because it was causing the phone to overheat.
A ministry spokesperson said it worked quickly to develop and implement fixes as soon as possible when an issue was identified, but it had had no reports of the app causing overheating.
"While we do not have enough information to speculate what caused overheating in the case of the screenshot you provided, we note that having a large number of active apps open at the same time could lead to a device overheating.
"Please note that while Bluetooth tracing is under consideration for the next major update to the app, the app does not currently use Bluetooth Low Energy or any other Bluetooth functionality.
"As with any app, minor problems are identified from time to time, some of which will only affect users with certain devices or operating systems."
In the Republic of Ireland, 83,000 deleted their contact tracing app after users complained about rapid depletion in battery life and overheating issues.
The NZ COVID Tracer app has been developed for the Ministry by New Zealand company Rush Digital.