This was due to technical issues with the plane.
Her flight from Copenhagen to Aarhus was delayed as a result of the issues and she was unable to secure a replacement flight at such short notice, causing her to miss the event.
Mary is sure to be devastated that she was unable to carry out her duties.
While the openings went ahead without the princess, it is currently unknown whether she will schedule a visit for a later date.
In the meantime, Mary is keeping busy with a number of other engagements.
On Friday, she will attend the Premiere of Armadeus at the Royal Danish Theatre in Copenhagen.
Later in the month she will make a trip to Switzerland to participate in a round table session to launch the CEO Agenda 2019 for the fashion industry.