Maven Class path error multiple SLF4J bindings

Question

I have been getting this error while trying to do a MAVEN INSTALL. I tried exclusions, but not sure the where to include in pom file. Let me how and what exclusion tags should i include in my pom file. I am also attaching my pom file snippet where to include the exclusions`SLF4J: Class path contains multiple SLF4J bindings.

SLF4J: Found binding in [jar:file:/C:/Users/147188/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar!/org/slf4j/impl/StaticLoggerBinder.class]

SLF4J: Found binding in [jar:file:/C:/Users/147188/.m2/repository/org/apache/logging/log4j/log4j-slf4j-impl/2.10.0/log4j-slf4j-impl-2.10.0.jar!/org/slf4j/impl/StaticLoggerBinder.class]

SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation. SLF4J: Actual binding is of type [ch.qos.logback.classic.util.ContextSelectorStaticBinder]

POM file:

<!-- Start of required part to make log4j work -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
    <exclusions>
    <exclusion>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
    </exclusion>
</exclusions> 
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter</artifactId>

    <exclusions>
    <exclusion>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
    </exclusion>
        <exclusion>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-logging</artifactId>
        </exclusion>
    </exclusions>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-log4j2</artifactId>
    <exclusions>
    <exclusion>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
    </exclusion>
</exclusions> 
</dependency>
        <!-- End of required part to make log4j work -->

Solution 1

1 Run

mvn dependency:tree

to see which package import org.slf4j

2 keep one, and exclude other

   <exclusion>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
    </exclusion>

Solution 2

Correct way to exclude default logging, and configure log4j for logging. Add this dependency in Spring Boot project, if it is not already there

<dependency>
 <groupId>org.springframework.boot</groupId>
 <artifactId>spring-boot-starter</artifactId>
 <exclusions>
     <exclusion>
     <groupId>org.springframework.boot</groupId>
     <artifactId>spring-boot-starter-logging</artifactId>
     </exclusion>
 </exclusions>
</dependency>

Refer Spring Logging - How To.

Solution 3

I ran into same log4j-slf4j multiple binding issue. There are multiple reasons which caused this issue (Struggled a lot for this issue :) ). Please find below comments.

1. I was using Spring-Boot version 1.4.7, which internally configured with slf4j-1.7.25 version. Below is the url link, where you can find Spring-Boot version and respective module versions.

https://repo1.maven.org/maven2/org/springframework/boot/spring-boot-dependencies/

It seems when you use "spring-boot-starter" dependency, SB(Spring-Boot) will automatically download all these dependent modules. In my project, i was using slf4j-1.7.21, which created multiple slf4j version issue. In short, SB was not able to identify which slf4j version to use at runtime. So, first I changed my slf4j version to 1.7.25(which is compatible with Spring-Boot version 1.4.7).

2. Next you need to exclude right module (in my case exclusion of log4j-over-slf4j, logback-classic worked). You need to add below exclusions in all of spring-boot-starter-** module. For Eg : Here I am adding exclusion for spring-boot-starter-data-redis.

Hope this will resolve issue.

Comments

[porlicus]

the only answer that helped me. thanx

[arvin_v_s]

to be more specific , you can use "mvn dependency:tree -Dincludes=:slf4j*"