An application with no custom HealthIndicator and management.health.defaults.enabled=false will return a 404. It used to be a 200 in 2.1.x:
HTTP/1.1 200
Content-Type: application/vnd.spring-boot.actuator.v2+json;charset=UTF-8
Date: Sat, 02 Nov 2019 07:06:31 GMT
Transfer-Encoding: chunked
{
"details": {
"application": {
"status": "UP"
}
},
"status": "UP"
}