How to Fix Errors After Updating Logback to Version 1.5.13 and Beyond

you’re working on your Java project, and you decide it’s time to update your dependencies to keep everything secure and up-to-date. You bump Logback from an older version to 1.5.13 or higher, hit run, and… bam! An error pops up, and your application won’t start. If this sounds familiar, you’re not alone. Many developers have faced unexpected issues after updating Logback to version 1.5.13 or later, and it can feel like a real headache. But don’t worry—I’m here to help you understand why these errors happen and how to fix them step-by-step.

In this guide, we’ll dive deep into the common errors that crop up after updating Logback to version 1.5.13 or higher. We’ll explore what’s changed in these versions, why your project might be breaking, and how you can get everything running smoothly again. Whether you’re a beginner or a seasoned coder, this article will give you clear, practical solutions in plain English. Let’s get started!

Table of contents

What Is Logback, and Why Update to 1.5.13?

Before we tackle the errors, let’s take a quick look at what Logback is and why updating it matters. Logback is a popular logging framework for Java applications. It’s fast, flexible, and reliable, making it a go-to choice for developers who need to track what’s happening in their code—think debugging, monitoring, or recording user activity. It’s built as a successor to Log4j and comes in three main modules: logback-core, logback-classic, and logback-access.

Updating to version 1.5.13 or higher is a smart move for a few reasons:

• Security Fixes: Newer versions patch vulnerabilities, keeping your app safe.
• Performance Boosts: Logback gets faster and more efficient with each release.
• New Features: Updates bring better tools, like improved configuration options.

But here’s the catch: with updates come changes, and those changes can sometimes break things if your setup isn’t ready. That’s where the errors come in. So, what exactly happens when you update to Logback 1.5.13 or later? Let’s find out.

Common Errors After Updating Logback to 1.5.13

When you update Logback to version 1.5.13 or higher, you might see errors like these:

1. “java.lang.NoClassDefFoundError”
   This one’s a classic. Your app crashes because a class it relied on is suddenly missing.

2. “IllegalStateException: Mandatory ‘class’ attribute missing for “
   Your logback.xml file throws a tantrum because something in your configuration isn’t right anymore.

3. “AbstractMethodError: getConfigurationLock()“
   This error shows up when Logback’s core classes don’t match up with other parts of your setup.

4. “No SLF4J providers were found”
   Your logging stops working entirely, and you’re left scratching your head.

These errors can feel overwhelming, but they all have one thing in common: they’re tied to changes introduced in Logback 1.5.13 and beyond. To fix them, we need to understand what changed.

What Changed in Logback 1.5.13?

Logback 1.5.13, released in early 2025, brought some big updates. While these changes improve the framework, they can trip up older configurations or dependencies. Here’s what’s different:

Removal of JaninoEventEvaluator

One of the biggest shifts in 1.5.13 is the removal of JaninoEventEvaluatorBase. This class was part of Logback’s filtering system, letting you write custom logic to decide which logs to keep or toss. Starting with 1.5.13, it’s gone, and you’ll need to replace it with a custom evaluator or adjust your setup.

Stricter Configuration Rules

Logback now enforces stricter rules in logback.xml. For example, the <evaluator> tag used to work without a class attribute in some cases. Now, it’s mandatory, and skipping it triggers an error.

Updated Core Interfaces

Some internal methods, like getConfigurationLock() in the Context interface, changed their return type (from Object to ReentrantLock). If other parts of your app (like logback-access) haven’t caught up, you’ll see compatibility errors.

SLF4J Compatibility

Logback 1.5.13 requires SLF4J 2.0.1 or higher. If your SLF4J version is older, Logback won’t find a logging provider, and your logs will vanish.

These changes are great for modernizing Logback, but they can break older projects. Let’s explore how to fix errors after updating Logback 1.5.13 with practical solutions.

How to Fix Errors After Updating Logback to 1.5.13

The key to fixing these errors is pinpointing the cause and applying the right solution. Below, I’ll walk you through each common issue with detailed steps. Pick the section that matches your error, and let’s get it sorted!

Fixing “NoClassDefFoundError: JaninoEventEvaluatorBase”

Why It Happens

This error pops up because JaninoEventEvaluatorBase was removed in Logback 1.5.13. If your logback.xml or code relies on it, Java can’t find it anymore.

How to Fix It

You’ve got two options:

1. Switch to a Custom Evaluator

   • Create your own evaluator by extending EventEvaluatorBase. Here’s a simple example:

     import ch.qos.logback.core.boolex.EventEvaluatorBase;
     import ch.qos.logback.core.spi.ContextAwareBase;
     
     public class CustomEvaluator extends EventEvaluatorBase<Object> {
         @Override
         public boolean evaluate(Object event) throws NullPointerException {
             // Your logic here, e.g., filter logs above DEBUG
             return event.toString().contains("DEBUG");
         }
     }

   • Update your logback.xml to use it:

     <evaluator name="MY_EVAL" class="com.example.CustomEvaluator">
         <expression>level > DEBUG</expression>
     </evaluator>

2. Downgrade to 1.5.12

   • If you don’t need 1.5.13’s features yet, revert to 1.5.12:

     <dependency>
         <groupId>ch.qos.logback</groupId>
         <artifactId>logback-classic</artifactId>
         <version>1.5.12</version>
     </dependency>

Quick Tip

The custom evaluator approach is better long-term—it keeps you on the latest version while fixing the issue.

Fixing “IllegalStateException: Mandatory ‘class’ attribute missing”

Why It Happens

In 1.5.13, Logback tightened its configuration rules. The <evaluator> tag now requires a class attribute to specify which evaluator to use.

How to Fix It

Check your logback.xml for <evaluator> tags. If they’re missing the class attribute, add it. For example:

• Old Config (Broken):

  <evaluator name="MY_EVAL">
      <expression>level > DEBUG</expression>
  </evaluator>

• New Config (Fixed):

  <evaluator name="MY_EVAL" class="com.example.CustomEvaluator">
      <expression>level > DEBUG</expression>
  </evaluator>

If you don’t have a custom evaluator yet, create one (see the previous section) or use a built-in alternative if available.

Fixing “AbstractMethodError: getConfigurationLock()“

Why It Happens

This error occurs when logback-core 1.5.13+ is paired with an older version of logback-access. The getConfigurationLock() method’s signature changed, and mismatched versions cause a compatibility clash.

How to Fix It

Update logback-access to a version compatible with 1.5.13. As of March 22, 2025, the latest is 2.0.6 or higher:

<dependency>
    <groupId>ch.qos.logback</groupId>
    <artifactId>logback-access</artifactId>
    <version>2.0.6</version>
</dependency>

Run mvn dependency:tree (for Maven) or gradle dependencies (for Gradle) to ensure all Logback modules align.

Fixing “No SLF4J providers were found”

Why It Happens

Logback 1.5.13 needs SLF4J 2.0.1 or newer. If your SLF4J version is older (like 1.7.x), Logback can’t connect to it.

How to Fix It

Update SLF4J in your project:

<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-api</artifactId>
    <version>2.0.12</version>
</dependency>

Then, reinstall Logback:

<dependency>
    <groupId>ch.qos.logback</groupId>
    <artifactId>logback-classic</artifactId>
    <version>1.5.13</version>
</dependency>

Check for conflicts with other logging frameworks (like Log4j) that might override SLF4J.

Step-by-Step Guide to Fix Errors After Updating Logback 1.5.13

Not sure which error you’re facing? Follow this general troubleshooting process:

1. Check Your Error Message

   • Look at the stack trace. Does it mention JaninoEventEvaluator, evaluator, getConfigurationLock, or SLF4J? That’s your clue.

2. Update All Dependencies

   • Use a dependency manager (Maven, Gradle) to align versions:

     <dependency>
         <groupId>ch.qos.logback</groupId>
         <artifactId>logback-core</artifactId>
         <version>1.5.13</version>
     </dependency>
     <dependency>
         <groupId>ch.qos.logback</groupId>
         <artifactId>logback-classic</artifactId>
         <version>1.5.13</version>
     </dependency>
     <dependency>
         <groupId>org.slf4j</groupId>
         <artifactId>slf4j-api</artifactId>
         <version>2.0.12</version>
     </dependency>

3. Review logback.xml

   • Look for outdated syntax (like <evaluator> without class) and update it.

4. Test in a Clean Environment

   • Create a virtual environment (python -m venv env for Python-like setups, or a new Maven/Gradle project) and test there.

5. Roll Back If Needed

   • If all else fails, revert to 1.5.12 until you can refactor.

Table: Common Errors and Fixes

Preventing Future Errors When Updating Logback

Now that you’ve fixed the error, how do you avoid this mess next time? Here are some tips:

• Read Release Notes: Check Logback’s official site for breaking changes before updating.
• Test in Staging: Try updates in a test environment first.
• Lock Versions: Use dependency management to keep Logback and SLF4J in sync.
• Backup Configs: Save your working logback.xml before tweaking it.

Conclusion: Mastering Logback Updates

Updating Logback to 1.5.13 or higher can throw some curveballs, but with the right know-how, you can fix errors after updating Logback 1.5.13 and keep your project humming along. Whether it’s swapping out JaninoEventEvaluator, tweaking your config, or syncing dependencies, you’ve now got the tools to handle it all.

Have you run into one of these errors? Try the fixes above and let me know how it goes—or if you hit a new snag, I’m here to help! Logging is the heartbeat of debugging, and with Logback back on track, your app will be better than ever.

Resources

• Logback Official Site
• Logback GitHub Repository
• SLF4J Documentation
• Maven Central Repository