Failed to load class “org.slf4j.impl.StaticLoggerBinder” error - maven

Question

I'm opening this post after I couldn't find a solution in the post:
Failed to load class "org.slf4j.impl.StaticLoggerBinder" error
I also opened a Maven project in IntelliJ and got the following error after choosing the option 'redeploy' in tomcat7 plugin:
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation SLF4J:
See http://www.slf4j.org/codes.html#StaticLoggerBinder for further
details.
In the attached link, it was recommended to go to File-> Project Structure -> Artifacts and check for errors. This is what I see:
I also have the following dependencies in pom.xml file:
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.5</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>1.5.6</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-simple</artifactId>
<version>1.7.21</version>
</dependency>
Can you please help me finding the error?

Answer 1

Maybe there are two issues:
version mismatching of your dependencies
an issue when you deploy your application
For reproducing your error I've created this mini program:
package de.so;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class DemoSlf4j
{
private static Logger logger = LoggerFactory.getLogger(DemoSlf4j.class);
public static void main(String[] args)
{
logger.error("Start ...");
}
}
with only these dependencies (same as you used) in pom.xml:
<dependencies>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.5</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>1.5.6</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-simple</artifactId>
<version>1.7.21</version>
</dependency>
</dependencies>
I've got these messages:
SLF4J: Class path contains multiple SLF4J bindings. SLF4J: Found
binding in
[jar:file:/D:/Maven-Repo/org/slf4j/slf4j-log4j12/1.5.6/slf4j-log4j12-1.5.6.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in
[jar:file:/D:/Maven-Repo/org/slf4j/slf4j-simple/1.7.21/slf4j-simple-1.7.21.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
[org.slf4j.impl.Log4jLoggerFactory] SLF4J: The requested version 1.5.6
by your slf4j binding is not compatible with [1.6, 1.7] SLF4J: See
http://www.slf4j.org/codes.html#version_mismatch for further details.
log4j:WARN No appenders could be found for logger (de.so.DemoSlf4j).
log4j:WARN Please initialize the log4j system properly.
When I use these dependencies, everything is fine. Look at the versions!
<dependencies>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.21</version> <!-- or use LATEST -->
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-simple</artifactId>
<version>1.7.21</version> <!-- or use LATEST -->
</dependency>
</dependencies>
If you are using org.slf4j:slf4j-log4j12:1.7.21 instead of slf4j-simple (what is more likely for production purposes), you'll get:
log4j:WARN No appenders could be found for logger (de.so.DemoSlf4j).
log4j:WARN Please initialize the log4j system properly. log4j:WARN See
http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
So do this:
look in your project dependencies if there are other artifacts which have cascading dependencies to logging frameworks (log4j, slf4f, ...).
check if your dependencies are proper deployed to your Tomcat. (.../WEB-INF/lib)
check the versions

Answer 2

Maybe you get cracked jar in your project ,check it in debug model detail,I had this problem too, when I build with debug model, I see warning of:
/repository/ch/qos/logback/logback-classic/1.1.11/logback-classic-1.1.11.jar ,so remove it ,and build it again. problem resolved.

Answer 3

You are providing a log api, and two different implementations, slf4j-log4j12 and slf4j-simple. I had the same issue, but in my case, it gave me an error message asking me to 'remove one' from class path.
You can try removing either slf4j-simple or slf4j-log4j12 from dependencies, clean and build project again.

Answer 4

I met with the same issue. I fixed it by adding the following dependencies to my POM.xml file:
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>${slf4j.version}</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-simple</artifactId>
<version>${slf4j.version}</version>
</dependency>
for the ${slf4j.version}, please assign the latest version number:
<properties>
...
<slf4j.version>1.7.30</slf4j.version>
</properties>