Hello SonarCloud 
users,
The /api/users/search endpoint will require authentication starting from the 18th of May. Since our logs show that this endpoint is sometimes used anonymously, we are planning a brown-out of anonymous access on the 4th of May, to raise awareness of this impending change. During the 24 hours of the brown-out the endpoint will require authentication.
If you are using this API endpoint please make sure you are authenticated.