The error, which could result in problems for people using the app to document vaccination when travelling, was confirmed by the Danish Health Data Authority (Sundhedsdatastyrelsen) in an email to broadcaster DR.
Newspaper Ekstra Bladet has reported the same issue.
The problem is related to the disappearance of the first dose from the data held by the app after the third dose has been registered, DR writes.
That can cause problems for travellers who use the app to document full vaccination status.
“It can cause challenges if you are travelling to countries which consider individuals to be fully vaccinated after a set period following the second dose. Because the first vaccination currently does not display, the (Coronapas) will appear to show that vaccination was not completed until quite recently,” the agency told DR.
The health data authority was expected to give a timeline for correction of the problem later on Tuesday.
Denmark has begun giving third Covid-19 vaccination shots to care home residents and selected people with compromised immune systems, but is yet to move on to other groups.