Police in Northern Ireland have apologised to 115 people who were stopped and searched by officers acting without correct authorisation.
Three of the searches, which took place between July 30 and August 11 this year, were of people aged under 18.
The error relates to how the stop and searches were authorised.
Under the Justice and Security Act, they can only be authorised by a chief officer or someone temporarily promoted to the role.
In the 115 actions in the summer, the authorisation was considered and signed by an individual who was an acting assistant chief constable rather than having been temporarily promoted to the role.
Explaining the issue, PSNI Assistant Chief Constable Barbara Gray said: "As soon as we became aware of the problem, we began a process to understand how the error had come about and what learning there is for the future.
"Part of that process included identifying those affected by the error and we have written to those individuals to inform them the stop and searches were invalid and to apologise for any inconvenience caused.
"We will continue to work with the Policing Board and the Independent Reviewer of Justice and Security around our use of our stop and search powers and will take forward any lessons learned from this technical error."
For the three individuals aged under 18, the force wrote to their parents or guardians to apologise.