SLF4J: Class path contains multiple SLF4J bindings


I'm getting the following error. It seems there are multiple logging frameworks bound to slf4j. Not sure how to resolve this. Any help is greatly appreciated.

SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/C:/Users/admin/.m2/repository/org/slf4j/slf4j-log4j12/1.6.4/slf4j-log4j12-1.6.4.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/C:/Users/admin/.m2/repository/org/slf4j/slf4j-log4j12/1.6.1/slf4j-log4j12-1.6.1.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See for an explanation.
8/3/2020 7:42:03 AM

Gradle version;

configurations.all {
    exclude module: 'slf4j-log4j12'

The error probably gives more information like this (although your jar names could be different)

SLF4J: Found binding in [jar:file:/D:/Java/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:/D:/Java/repository/org/apache/logging/log4j/log4j-slf4j-impl/2.8.2/log4j-slf4j-impl-2.8.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]

Noticed that the conflict comes from two jars, named logback-classic-1.2.3 and log4j-slf4j-impl-2.8.2.jar.

Run mvn dependency:tree in this project pom.xml parent folder, giving:

dependency tree conflict

Now choose the one you want to ignore (could consume a delicate endeavor I need more help on this)

I decided not to use the one imported from spring-boot-starter-data-jpa (the top dependency) through spring-boot-starter and through spring-boot-starter-logging, pom becomes:


in above pom spring-boot-starter-data-jpa would use the spring-boot-starter configured in the same file, which excludes logging (it contains logback)


Sbt version:

Append exclude("org.slf4j", "slf4j-log4j12") to the dependency that transitively includes slf4j-log4j12. For example, when using Spark with Log4j 2.6:

libraryDependencies ++= Seq(
  // One SLF4J implementation (log4j-slf4j-impl) is here:
  "org.apache.logging.log4j" % "log4j-api" % "2.6.1",
  "org.apache.logging.log4j" % "log4j-core" % "2.6.1",
  "org.apache.logging.log4j" % "log4j-slf4j-impl" % "2.6.1",
  // The other implementation (slf4j-log4j12) would be transitively
  // included by Spark. Prevent that with exclude().
  "org.apache.spark" %% "spark-core" % "1.5.1" exclude("org.slf4j", "slf4j-log4j12")


I solved by delete this:spring-boot-starter-log4j2


I just ignored/removed that jar file.

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