This is my Spring Boot 1.5.1 Actuator application.properties:
application.properties
#Spring Boot Actuator management.contextPath: /actuator management.security.roles=R_0
You have to use prefix ROLE_ for your management.security.roles for example management.security.roles=ROLE_SOMENAME in order to solve this issue
ROLE_
management.security.roles
management.security.roles=ROLE_SOMENAME