The default strategy assumes that if you don’t have a logback.xml (or one of the other standard file names) in the classpath then you must be happy with the defaults (see LogbackLoggingSystem for details). Spring Boot tries to unify the external configuration switches for common logging sytems, so it looks in logging.config (it didn’t know about logback.configurationFile). You could use that instead (i.e. logging.config=file:./src/test/resources/logback.xml), or make sure your config file is on the classpath.