Gradle Build Failure: Upgrade Org.asciidoctor.jvm.convert?

Nov 12, 2025 by Alex Johnson 59 views

Experiencing issues building your Gradle project with org.asciidoctor.jvm.convert version 3.3.2? You're not alone! Many developers have encountered similar problems, particularly when using recent versions of Spring Boot and Java. This article dives into the root cause of this issue, provides a step-by-step guide to resolving it, and explains why upgrading to the latest version of org.asciidoctor.jvm.convert is often the best solution. Let’s explore this common problem and how to fix it, ensuring your Spring Boot projects build smoothly.

Understanding the Problem

The core issue manifests as an Unable to load class 'org.gradle.util.CollectionUtils' error during the Gradle build process. This perplexing message often appears when using a minimal start.spring.io project configured with:

Project: Gradle Kotlin
Language: Java 21 or higher
Spring Boot: 3.2.0 or higher (including Release Candidates like 4.0.0-RC2 and RC1)
Dependencies: Spring Rest Docs and Spring Web

The error stems from the interaction between the org.asciidoctor.jvm.convert plugin, Gradle, and newer versions of Spring Boot and Java. Specifically, version 3.3.2 of the plugin has compatibility issues with the newer Gradle APIs and dependencies used in these environments. When Gradle attempts to load the org.gradle.util.CollectionUtils class, it fails, halting the build process. This can be a significant roadblock, especially when you're trying to leverage the latest features of Spring Boot and Java.

Why does this happen? The org.asciidoctor.jvm.convert plugin, in its older versions, relies on certain internal Gradle classes and APIs. As Gradle evolves, these internal APIs can change or be removed, leading to compatibility issues. Version 3.3.2, in particular, was released before some of the significant changes in Gradle's internal structure, making it incompatible with the newer versions used by recent Spring Boot projects. Therefore, understanding the root cause helps in recognizing the importance of keeping dependencies updated to avoid such conflicts.

Diagnosing the Issue: Recognizing the Error Message

The most telling sign of this issue is the error message itself:

Unable to load class 'org.gradle.util.CollectionUtils'.

This is an unexpected error. Please file a bug containing the idea.log file.

If you encounter this message during your Gradle build, especially within a Spring Boot project, it's a strong indicator that the org.asciidoctor.jvm.convert plugin is the culprit. The error message is quite specific, pointing directly to the class loading failure. However, it's crucial to differentiate this from other class loading issues that might arise from different dependencies or configurations. Key indicators that this specific issue is at play include:

The presence of the org.asciidoctor.jvm.convert plugin in your project’s dependencies.
The use of Spring Boot 3.2.0 or higher.
The use of Java 21 or higher.
The inclusion of Spring Rest Docs as a dependency, as it often triggers the use of Asciidoctor.

To further confirm, you can examine your build.gradle.kts or build.gradle file and check the version of org.asciidoctor.jvm.convert. If it’s 3.3.2, you’ve likely pinpointed the problem. Additionally, reviewing the stack trace or build logs might reveal that the error occurs during the execution of an Asciidoctor task, providing further evidence. By recognizing these indicators, you can quickly diagnose the problem and move towards implementing the solution.

The Solution: Upgrading `org.asciidoctor.jvm.convert`

The most effective solution to this problem is to upgrade the org.asciidoctor.jvm.convert plugin to a more recent version. The latest version, as of this writing, is 4.0.5, which includes fixes and compatibility improvements that address the class loading issue. Upgrading ensures that your project benefits from the latest features and bug fixes, making it compatible with current versions of Gradle, Spring Boot, and Java. Let's walk through the steps to upgrade this crucial dependency.

Step-by-Step Upgrade Guide:

Locate your build file: Open your project’s build.gradle.kts (for Kotlin DSL) or build.gradle (for Groovy DSL) file. This file is located in the root directory of your project and contains all the dependency configurations.
Find the org.asciidoctor.jvm.convert dependency: Search for the line that declares the dependency on org.asciidoctor.jvm.convert. It will typically look something like this:
- For Kotlin DSL: id("org.asciidoctor.jvm.convert") version "3.3.2"
- For Groovy DSL: id 'org.asciidoctor.jvm.convert' version '3.3.2'
Update the version: Change the version number from 3.3.2 to the latest version, 4.0.5 (or a newer stable release if available). The updated line should look like this:
- For Kotlin DSL: id("org.asciidoctor.jvm.convert") version "4.0.5"
- For Groovy DSL: id 'org.asciidoctor.jvm.convert' version '4.0.5'
Sync Gradle: After updating the version, you need to sync Gradle to apply the changes. In IntelliJ IDEA or other IDEs, you can find a “Sync Gradle” button or option in the Gradle tool window. Alternatively, you can run the command ./gradlew --refresh-dependencies from your project's root directory.
Clean and rebuild: To ensure that the changes are fully applied, clean and rebuild your project. You can do this by running the following Gradle commands:
- ./gradlew clean
- ./gradlew build

Example Snippets:

Kotlin DSL (build.gradle.kts):

plugins {
    kotlin("jvm") version "1.9.21"
    id("org.springframework.boot") version "3.2.0"
    id("io.spring.dependency-management") version "1.1.4"
    id("org.asciidoctor.jvm.convert") version "4.0.5" // Updated version
}

Groovy DSL (build.gradle):

plugins {
    id 'org.springframework.boot' version '3.2.0'
    id 'io.spring.dependency-management' version '1.1.4'
    id 'org.asciidoctor.jvm.convert' version '4.0.5' // Updated version
    id 'java'
}

By following these steps, you can effectively upgrade the org.asciidoctor.jvm.convert plugin, resolving the class loading issue and ensuring your Gradle build runs smoothly. It's crucial to keep your dependencies updated to avoid such compatibility conflicts and take advantage of the latest improvements and features.

Why Upgrading Works: Addressing Compatibility Issues

Upgrading org.asciidoctor.jvm.convert resolves the Unable to load class error because newer versions of the plugin are designed to be compatible with the latest Gradle APIs and dependency structures. When you upgrade, you're essentially replacing an older version that relies on deprecated or removed Gradle functionalities with a newer version that uses the current, supported APIs. This is a critical step in maintaining the health and stability of your project.

Compatibility with Gradle and Spring Boot:

The primary reason upgrading works is that version 4.0.5 (and later) of org.asciidoctor.jvm.convert has been specifically updated to align with the changes in Gradle and Spring Boot. Newer versions of Gradle have evolved their internal APIs, and Spring Boot, in turn, leverages these Gradle improvements. The older version 3.3.2, released before these changes, uses Gradle APIs that are no longer available or have been significantly altered. By upgrading, you ensure that the plugin can correctly interact with the current Gradle environment.

Dependency Management:

Upgrading also ensures that the plugin’s dependencies are up-to-date. Older versions might rely on outdated dependencies that conflict with those used by newer Spring Boot versions. By upgrading org.asciidoctor.jvm.convert, you often pull in newer versions of its transitive dependencies, resolving potential conflicts and ensuring a consistent dependency tree.

Bug Fixes and Improvements:

Beyond compatibility, newer versions of the plugin often include bug fixes and performance improvements. Upgrading can resolve not only the class loading issue but also other potential problems that might exist in older versions. These improvements can lead to a more stable and efficient build process, saving you time and reducing frustration. Staying current with the latest releases is a best practice in software development, and this case is a prime example of why.

In summary, upgrading org.asciidoctor.jvm.convert is not just a workaround; it's a comprehensive solution that addresses compatibility, dependency management, and overall plugin stability. This proactive approach ensures your project can leverage the latest technologies without encountering preventable build errors.

Alternative Solutions (If Upgrading Isn't Immediately Possible)

While upgrading org.asciidoctor.jvm.convert is the recommended solution, there might be scenarios where an immediate upgrade isn't feasible. Perhaps you're working on a legacy project with strict versioning requirements, or you need to thoroughly test the upgrade in a separate environment before deploying it to production. In such cases, there are alternative approaches you can consider, though they are generally less ideal than upgrading.

Downgrade Gradle Version:
- One potential workaround is to downgrade your Gradle version to one that is compatible with org.asciidoctor.jvm.convert 3.3.2. This can be a temporary fix, but it's not recommended as a long-term solution. Older Gradle versions might have their own bugs and lack the latest features and performance improvements. Additionally, downgrading can introduce compatibility issues with other plugins and dependencies in your project.
- How to Downgrade: In your gradle/wrapper/gradle-wrapper.properties file, change the distributionUrl to point to an older Gradle version. For example, to downgrade to Gradle 7.6, you would modify the line to:
```
distributionUrl=https\://services.gradle.org/distributions/gradle-7.6-bin.zip
```
- After changing the version, run ./gradlew wrapper to update the Gradle wrapper.
Exclude org.gradle.util.CollectionUtils (Not Recommended):
- In theory, you could try to exclude the problematic class, org.gradle.util.CollectionUtils, but this is highly discouraged. This class is part of Gradle's internal API, and excluding it can lead to unpredictable behavior and potentially break other parts of your build process. This approach is more of a hack than a solution and is likely to cause more problems than it solves.
Use a Specific Version of the Asciidoctor Gradle Plugin:
- If you are using the Asciidoctor Gradle plugin directly, ensure you are using a version that is compatible with org.asciidoctor.jvm.convert 3.3.2. However, this approach still doesn't address the core issue of using an outdated version and is not a recommended long-term solution.

Important Considerations:

Testing: If you opt for an alternative solution, thoroughly test your build and application to ensure that everything functions as expected. Workarounds can sometimes have unintended side effects.
Documentation: Document any workarounds you implement. This will help other developers understand the changes and the reasons behind them, and it will make it easier to revert to the recommended solution (upgrading) in the future.
Long-Term Strategy: Treat these alternative solutions as temporary measures. Plan to upgrade org.asciidoctor.jvm.convert as soon as it's feasible to ensure long-term compatibility and stability.

In conclusion, while alternative solutions might provide temporary relief, upgrading org.asciidoctor.jvm.convert remains the most robust and future-proof approach to resolving the Unable to load class error. Always prioritize upgrading when possible to maintain a healthy and up-to-date project.

Preventing Future Issues: Best Practices for Dependency Management

To minimize the chances of encountering similar issues in the future, adopting proactive dependency management practices is crucial. Dependency management is not just about resolving immediate conflicts; it's about establishing a sustainable approach to keeping your project’s dependencies healthy and up-to-date. By implementing these best practices, you can reduce the risk of compatibility problems, security vulnerabilities, and unexpected build failures.

Keep Dependencies Updated Regularly:
- The Principle: Regularly update your project’s dependencies to their latest stable versions. Outdated dependencies are a common source of bugs, security vulnerabilities, and compatibility issues. Staying current ensures that you benefit from the latest bug fixes, performance improvements, and security patches.
- How to Implement: Schedule regular dependency update reviews. Use tools like Dependabot (for GitHub) or similar services that automatically monitor your dependencies and create pull requests for updates. Review and test these updates thoroughly before merging them.
Use a Dependency Management Tool:
- The Principle: Employ a robust dependency management tool like Gradle or Maven. These tools automate the process of resolving dependencies, managing versions, and handling transitive dependencies (dependencies of your dependencies). They ensure consistency and reduce the risk of conflicts.
- How to Implement: Spring Boot projects typically use Gradle or Maven. Leverage the features of these tools, such as dependency version locking (using Gradle’s version catalog or Maven’s <dependencyManagement> section) to ensure consistent builds across different environments.
Lock Dependency Versions:
- The Principle: Pin your dependency versions to specific releases rather than using dynamic version ranges (e.g., 2.+). Dynamic ranges can lead to unpredictable behavior as newer versions are released, potentially introducing breaking changes without you realizing it.
- How to Implement: Specify exact versions in your build.gradle.kts or pom.xml file. For example, use `implementation(