Failed to instantiate SLF4J LoggerFactory when using slf4j with log4j2

Question

I'm starting to use slf4j with log4j2 but I got the problem as below. What am I wrong or lack somethings of from the pom file?

Failed to instantiate SLF4J LoggerFactory

Reported exception:

java.lang.NoClassDefFoundError: org/apache/logging/log4j/spi/AbstractLoggerAdapter

at java.lang.ClassLoader.defineClass1(Native Method)

at java.lang.ClassLoader.defineClass(ClassLoader.java:763)

at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)

at java.net.URLClassLoader.defineClass(URLClassLoader.java:468)

at java.net.URLClassLoader.access$100(URLClassLoader.java:74)

...

My pom.xml:

<dependencies>
    <!-- https://mvnrepository.com/artifact/org.slf4j/slf4j-api -->
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>1.7.30</version>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-slf4j-impl</artifactId>
        <version>2.12.0</version>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-api</artifactId>
        <version>2.13.3</version>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-core</artifactId>
        <version>2.13.3</version>
    </dependency>

</dependencies>

My very simple code:

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class Study {

    static Logger LOGGER = LoggerFactory.getLogger(Study.class);
    public static void main(String... args) {
        LOGGER.info("hello world");
    }
}

Using different versions `2.12.0` and `2.13.3` is on purpose? — Progman, Nov 05 '20 at 17:24
I just use the run functionality in intelliJ to run the main method (right click in Class Study and run the main()) — Nghia Tran, Nov 05 '20 at 18:54
Unless you have an existing codebase that is using sl4j you don't really need to use it for log4j2 and in fact you lose a lot of the features of log4j2 if you do. See https://stackoverflow.com/a/41500347/3284624 — D.B., Nov 06 '20 at 02:45

score 0 · Answer 1 · answered Nov 05 '20 at 17:22

Try to use the same version for all libs from one groupId:

...
<dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-slf4j-impl</artifactId>
        <version>2.13.3</version>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-api</artifactId>
        <version>2.13.3</version>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-core</artifactId>
        <version>2.13.3</version>
    </dependency>
...

Also, you can try running without org.slf4j dependency. Run mvn clean install before the start.

score 0 · Answer 2 · answered Nov 05 '20 at 19:32

I don't know what is the reason but if I use 2.11.2, it works

<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-api</artifactId>
    <version>1.7.30</version>
</dependency>
<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-slf4j-impl</artifactId>
    <version>2.11.2</version>
</dependency>
<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-api</artifactId>
    <version>2.11.2</version>
</dependency>
<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-core</artifactId>
    <version>2.11.2</version>
</dependency>

Failed to instantiate SLF4J LoggerFactory when using slf4j with log4j2

2 Answers2