Why maven sometimes can't resolve dependencies?
You have declared 'org.springframework.boot' as the parent module of both modules. So if some jars and artifacts like 'com.amazonaws' do not exist in 'org.springframework.boot', they won't be resolved in your project. These dependencies are not announced in 'Spring' module in your project and whatever you have declared in it, can be found in 'org.springframework.boot', then resolved. If you do not declare a 'version' tag in your pom, I guess the version of the parent (here 2.6.1) will be considered for your module version.