LoggerFactory is not a Logback LoggerContext but Logback is on the classpath

Question

I think some module in spring-boot-starter-security is conflict with log4j, but I don't know which one.

my gradle dependence is as following:

compile("org.springframework.boot:spring-boot-starter-thymeleaf")
compile("org.springframework.boot:spring-boot-starter-security"){
    exclude module: "spring-boot-starter-logging"
}

compile "org.apache.logging.log4j:log4j-api"
compile "org.apache.logging.log4j:log4j-core"
compile "org.apache.logging.log4j:log4j-slf4j-impl"
compile('org.apache.poi:poi:3.10.1')
compile('org.apache.poi:poi-ooxml:3.10.1')
testCompile("junit:junit")

Answer 1

i figured out

compile("org.springframework.boot:spring-boot-starter-security"){
    exclude module: "spring-boot-starter-logging"
    exclude module: "logback-classic"
}
compile("org.springframework.boot:spring-boot-starter-thymeleaf"){
    exclude module: "logback-classic"
}

Answer 2

For me this problem appeared only during execution of maven-surefire-plugin. Somehow Logback is there on the class path, even if its not added to project dependencies. I added such fix:

<plugin>
     <groupId>org.apache.maven.plugins</groupId>
     <artifactId>maven-surefire-plugin</artifactId>
     <version>${maven-surefire-plugin.version}</version>
     <configuration>
        <systemPropertyVariables>
            <org.springframework.boot.logging.LoggingSystem>
                org.springframework.boot.logging.log4j2.Log4J2LoggingSystem
            </org.springframework.boot.logging.LoggingSystem>
        </systemPropertyVariables>
    </configuration>
</plugin>

You can also use

mvn clean install -Dorg.springframework.boot.logging.LoggingSystem=org.springframework.boot.logging.log4j2.Log4J2LoggingSystem

Answer 3

According to this bug, the bundled and undeletable Kotlin plugin (reminds me the forced inclusion of U2's album with iOS) includes org.gradle.kotlin.kotlin-dsl, which in turn pollutes the classpath with an incompatible logging library (even if disabled).

I solved this by changing the runner from "IntelliJ IDEA" to "Gradle" in preferences:

• Build, Execution, Deployment
  • Build Tools
    • Gradle
      • Build an run using -> Gradle
      • Run tests using -> Gradle

Answer 4

Started seeing this error after including 'it.ozimov:embedded-redis:0.7.3' I had to change

testImplementation 'it.ozimov:embedded-redis:0.7.3'

to

testImplementation ('it.ozimov:embedded-redis:0.7.3') {
    exclude module: 'commons-logging'
    exclude module: 'slf4j-simple'
}

and the issue is resolved.

Answer 5

It should be told that after trying to exclude every logback artifact I found which didn't work for me, I just deleted the maven-folder (/.m2). After another

mvn clean install

everything started fine and the error never appeared again. I by the way removed every Exclusion i did before. Still working

Answer 6

works for me:

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
        <exclusions>
            <!-- avoid: LoggerFactory is not a Logback LoggerContext but Logback is on the classpath. on run with vscode -->
            <exclusion>
                <groupId>ch.qos.logback</groupId>
                <artifactId>logback-classic</artifactId>
            </exclusion>
        </exclusions>
    </dependency>

Answer 7

Per @Bohemian 's post:

Removing this fixed it for me:

plugins {
    `kotlin-dsl`
}

Bug reference from @Bohemian

This plugin is recommended to be added to gradle files for the kotlin dsl, but I found that it really isn't needed... syntax highlighting still worked for me afterwards and I didn't see any issues after removing it. In fact it removed the issue mentioned in this thread to remove it.

Answer 8

Same solution for maven:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-thymeleaf</artifactId>
    <version>1.5.1.RELEASE</version>
    <exclusions>
        <exclusion>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
        </exclusion>
    </exclusions>
</dependency>

Answer 9

The problem for me went on with: Either remove Logback or the competing implementation class org.apache.logging.slf4j.Log4jLoggerFactory loaded from log4j-slf4j-impl-2.12.0.jar

I added

configurations {
    all {
        exclude group: 'org.springframework.boot', module: 'spring-boot-starter-logging'
        exclude group: 'ch.qos.logback', module: 'logback-classic'
        exclude group: 'org.apache.logging.log4j', module: 'log4j-to-slf4j'
    }
}

to my gradle.build and also refreshed all project dependencies with the latest versions and the problem resolved.

Answer 10

According to this documentation, Spring Boot automatically configures the Log Back library because of the web starter. You should exclude the spring-boot-starter-logging to fix the issue.

To exclude the default LogBack configuration on the gradle project,

configurations {
    all*.exclude module : 'spring-boot-starter-logging'
    all*.exclude module : 'logback-classic'
}

Answer 11

            <exclusions>
                <exclusion>
                    <groupId>org.slf4j</groupId>
                    <artifactId>slf4j-simple</artifactId>
                </exclusion>
            </exclusions>

For me this was the fix, because OpenAPI Generator was bringing this and it conflicted with SpringsBoot Default. So once I excluded this one, the SpringBootApp started working.

Answer 12

Using the IDEA "Show Dependencies" or mvn dependency:tree -Dverbose to find all the logback-classic jar file, and exclude them.