quarkusio/quarkus · error · IllegalStateException

Multiple extensions registered a feature of the same name: $

Error message

Multiple extensions registered a feature of the same name: ${feature.getName()}

What it means

Each extension normally registers one named FeatureBuildItem for logging/feature reporting. During main-class generation Quarkus collects all features for the startup log line; if two extensions registered a feature with the identical name the build fails fast with this IllegalStateException.

Source

Thrown at core/deployment/src/main/java/io/quarkus/deployment/steps/MainClassBuildStep.java:336

                    ofMethod(RuntimeInfoProvider.class, "register", void.class, ValueRegistry.class, RuntimeSource.class),
                    runtimeInfoProvider,
                    valueRegistry,
                    tryBlock.invokeStaticMethod(ofMethod(ConfigRuntimeSource.class, "runtimeSource", RuntimeSource.class)));
        }

        for (MainBytecodeRecorderBuildItem holder : mainMethod) {
            writeRecordedBytecode(holder.getBytecodeRecorder(), holder.getGeneratedStartupContextClassName(), substitutions,
                    recordableConstructorBuildItems,
                    loaders, constants, gizmoOutput, startupContext, tryBlock);
        }

        tryBlock.invokeStaticMethod(RUNTIME_EXECUTION_RUNNING);

        // Startup log messages
        List<String> featureNames = new ArrayList<>();
        for (FeatureBuildItem feature : features) {
            if (featureNames.contains(feature.getName())) {
                throw new IllegalStateException(
                        "Multiple extensions registered a feature of the same name: " + feature.getName());
            }
            featureNames.add(feature.getName());
        }
        ResultHandle featuresHandle = tryBlock.load(featureNames.stream().sorted().collect(Collectors.joining(", ")));
        tryBlock.invokeStaticMethod(
                ofMethod(Timing.class, "printStartupTime", void.class, String.class, String.class, String.class, String.class,
                        List.class, boolean.class, boolean.class),
                tryBlock.load(applicationInfo.getName()),
                tryBlock.load(applicationInfo.getVersion()),
                tryBlock.load(Version.getVersion()),
                featuresHandle,
                tryBlock.invokeStaticMethod(ofMethod(ConfigUtils.class, "getProfiles", List.class)),
                tryBlock.load(LaunchMode.DEVELOPMENT.equals(launchMode.getLaunchMode())),
                tryBlock.load(launchMode.isAuxiliaryApplication()));

        tryBlock.invokeStaticMethod(
                ofMethod(QuarkusConsole.class, "start", void.class));

View on GitHub (pinned to e1c734241f)

Solutions

Identify which extensions produce the duplicate name from the build output and remove one of the extensions/forks
If it's your own build step, rename the feature string to a unique value
Upgrade/align extension versions — older collisions are usually fixed in newer releases
Report/patch the offending third-party extension to use a distinct feature name

Example fix

// before (custom build step)
return List.of(new FeatureBuildItem("hibernate"));
// after
return List.of(new FeatureBuildItem("my-custom-hibernate-integration"));

Defensive patterns

Strategy: validation

Validate before calling

Set<String> names = new HashSet<>();
for (var f : features) {
    if (!names.add(f.getName())) {
        throw new IllegalStateException("Duplicate feature name: " + f.getName());
    }
}

Try / catch

try {
    quarkusBuild();
} catch (IllegalStateException e) {
    if (e.getMessage() != null && e.getMessage().startsWith("Multiple extensions registered a feature")) {
        // inspect extensions for the duplicated feature name and remove/patch one
    }
    throw e;
}

Prevention

Give custom FeatureBuildItems unique, project-prefixed names
Avoid including two forks of the same extension
Keep third-party extensions updated where name collisions were fixed
Grep your build steps for FeatureBuildItem names when adding extensions

When it happens

Trigger: During MainClassBuildStep.build, iterating features and finding the same feature name twice — two extensions (or one extension twice) produced FeatureBuildItems with equal names.

Common situations: Two different extensions picked the same feature name (often after a rename/merge); an application's custom build step registers a FeatureBuildItem whose name collides with an existing extension (e.g. 'hibernate'); including two forks of the same extension.

Related errors

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/c12ee93be83660b8. Report an issue: GitHub.