Property 'spring.profiles.active' imported from location 'class path resource [application-dev.yml]' is invalid

Solution 1:

Spring Boot 2.4 has improved the way that application.properties and application.yml files are processed.

See here for details: https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-Config-Data-Migration-Guide

Long story short: If you have for example an application-local.yml and inside you defined

spring:
profiles:
    active: local 

then just remove this entry in the yaml file.

Solution 2:

No need to mention spring.profiles.active property if file name is application-dev.yml ( spring boot new version )

Solution 3:

In your application-dev.yml, you declare :

spring:
    application:
        name: mail-service
    profiles:
        active: local 

2 solutions :

1. rename application-dev.yml to application-local.yml and use local profile
2. change spring.profiles.active to dev in application-dev.yml