I'm getting “NoClassDefFoundError: org/apache/logging/log4j/util/ReflectionUtil”

Question

I have the following dependencies in my build.gradle file.

compile \'org.slf4j:slf4j-api:1.7.25\'
compile group: \'org.apache.logging.log4j\', name: \'log4j-         


        

Answer 1

The error: java.lang.NoClassDefFoundError: org/apache/logging/log4j/util/ReflectionUtil

is because log4j2 since version 2.9.0 has been removed that class from api jar (log4j-api-2.x.x.jar).

The last version that has it, is 2.8.2

Probably you have mixed versions in the classpath.

Answer 2

Correct way to configure log4j2 in spring boot is like this:

dependencies {
    compile 'org.springframework.boot:spring-boot-starter-web'
    compile 'org.springframework.boot:spring-boot-starter-log4j2'
}

configurations {
    all {
        exclude group: 'org.springframework.boot', module: 'spring-boot-starter-logging'
    }
}

It's explained in the documentation.