The Covid Tracer App notifications for some people who were at a location of interest have recently been delayed by a day.
In a statement, the Ministry of Health said it was due to an "intermittent technical issue".
It affected people who were at some "of the larger festivals in the past two weeks", the ministry said.
Notifications have now been sent out with the issue resolved.
The ministry is recommending people check the locations of interest page online which is updated frequently.