Loggerfactory is not a logback loggercontext but logback is on the classpath

This error message occurs when the application is attempting to create a logger context using LoggerFactory, but the actual logger context is not from Logback. However, Logback library is present in the classpath.

To understand this error, we need to understand how LoggerFactory and LoggerContext work in Logback.

LoggerFactory is a class in Logback that provides methods to retrieve or create Logback loggers. It internally looks for the ContextSelector and gets the current logger context associated with the application.

LoggerContext is the actual implementation class that represents the logger context in Logback. It manages the loggers, appenders, filters, and other configurations for logging.

When the application tries to create a logger context using LoggerFactory, it expects the logger context returned to be from Logback. But in this case, it is not from Logback, resulting in the mentioned error message.

Here’s an example to illustrate this scenario:

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

public class MyApplication {
    private static final Logger LOGGER = LoggerFactory.getLogger(MyApplication.class);

    public static void main(String[] args) {
        LOGGER.info("Hello, World!");
    }
}
    
  

In the above example, the application tries to create a logger using LoggerFactory.getLogger(MyApplication.class), assuming that the returned logger is backed by Logback. But if the actual logger context implementation is not from Logback, the error will occur.

To resolve this issue, you need to ensure that Logback is properly configured as the logger provider in your application. This typically involves adding the Logback dependencies to your project’s build configuration and configuring the logback.xml file to define the logger context.

For example, in a Maven project, you can add the following dependencies to your pom.xml file:

    
<dependencies>
    <!-- Logback dependencies -->
    <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-classic</artifactId>
        <version>1.2.3</version>
    </dependency>
    <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-core</artifactId>
        <version>1.2.3</version>
    </dependency>
</dependencies>
    
  

Additionally, make sure to provide a valid logback.xml configuration file in your application’s classpath. This file defines the logging configuration, including the logger context, appenders, and other settings.

Here’s an example logback.xml configuration file:

    
<configuration>
    <!-- Define logger context -->
    <contextName>myLoggerContext</contextName>
    
    <!-- Define appenders, loggers, and other configurations -->
    ...
</configuration>
    
  

By ensuring that Logback is properly configured and the logger context is from Logback, you can resolve the error and use Logback for logging in your application.