quarkusio/quarkus · error · RuntimeException

because the project does not have any source set / among the

Error message

because the project does not have any source set / among the following source sets:

What it means

Thrown by GradleApplicationModelBuilder.processDeploymentDependency when a Quarkus deployment dependency (artifactId ending in -deployment) resolves to a Gradle project whose source sets contain no match for the required source set. The builder needs to associate the deployment artifact with a source set of the main application project; when none exists or none of the available source sets can be matched, it aborts with a RuntimeException listing the source sets it inspected. This indicates the Gradle project structure is inconsistent with what Quarkus expects.

Source

Thrown at devtools/gradle/gradle-model/src/main/java/io/quarkus/gradle/tooling/GradleApplicationModelBuilder.java:313

                    SourceSetContainer sourceSets = projectDep.getExtensions().getByType(SourceSetContainer.class);

                    SourceSet mainSourceSet = sourceSets.findByName(SourceSet.MAIN_SOURCE_SET_NAME);
                    if (mainSourceSet == null) {
                        // try Kotlin multiplatform
                        mainSourceSet = sourceSets.findByName("jvmMain");
                        if (mainSourceSet == null) {
                            var msg = new StringBuilder()
                                    .append("Failed to determine the main source set of ").append(projectDep.getPath());
                            var i = sourceSets.iterator();
                            if (!i.hasNext()) {
                                msg.append(" because the project does not have any source set");
                            } else {
                                msg.append(" among the following source sets: ").append(i.next().getName());
                                while (i.hasNext()) {
                                    msg.append(", ").append(i.next().getName());
                                }
                            }
                            throw new RuntimeException(msg.toString());
                        }
                    }
                    dep = toDependency(a, mainSourceSet);
                    modelBuilder.addDependency(dep);
                } else if (isDependency(a)) {
                    dep = toDependency(a);
                    modelBuilder.addDependency(dep);
                }
                if (dep != null) {
                    modelBuilder.addDependency(dep);
                    clearReloadableFlag = true;
                }
            }
            if (dep != null) {
                if (dep.isRuntimeExtensionArtifact()) {
                    clearReloadableFlag = true;
                }
                dep.setDeploymentCp();

View on GitHub (pinned to e1c734241f)

Solutions

Ensure the subproject providing the Quarkus extension has a 'main' source set (apply the java/kotlin plugin and keep the default source set intact).
Check which source sets are listed in the message; add or rename your source set so it matches what the Quarkus Gradle plugin expects.
Verify the deployment dependency (artifactId-suffix '-deployment') points to the intended project in your Gradle dependency declarations.
Align the Quarkus Gradle plugin version with your Quarkus platform/BOM version to avoid mismatched model-building assumptions.
Run with --stacktrace/-Dorg.gradle.debug to confirm which dependency triggers it and fix that module's configuration.

Example fix

// before (build.gradle of a subproject with no java plugin)
plugins { id 'io.quarkus' }
// after
plugins { id 'java'; id 'io.quarkus' }
sourceSets { main { java { srcDirs 'src/main/java' } } }

Defensive patterns

Strategy: validation

Validate before calling

// In your Gradle build, before invoking Quarkus tasks:
def ss = project.sourceSets.findByName('main')
if (ss == null) throw new GradleException("Project ${project.name} has no 'main' source set required by the Quarkus Gradle plugin")

Try / catch

try {
    quarkusBuild()
} catch (RuntimeException e) {
    if (e.message?.contains('among the following source sets')) {
        logger.error('Quarkus deployment dependency could not be mapped to a source set: ' + e.message)
    } else throw e
}

Prevention

Always apply the java (or kotlin) plugin in projects that use the Quarkus plugin
Do not rename or remove the default 'main' source set in Quarkus modules
Keep the Quarkus Gradle plugin version aligned with the Quarkus platform version
Run ./gradlew tasks in CI early to catch model-building failures before full builds

When it happens

Trigger: Running a Quarkus Gradle build (quarkusDev, quarkusBuild, or the model-building phase) where collectExtensionDependencies walks deployment dependencies and calls processDeploymentDependency on a project dependency that has no matching source set — e.g. the deployment artifact maps to a project whose main source set was not created, or the required source set name does not exist among the project's source sets.

Common situations: Multi-project Gradle builds where a library subproject's quarkus deployment dependency is wired to the wrong project; custom source set configurations (renaming/removing the 'main' source set); applying the Quarkus plugin in a project with no Java/Kotlin source sets; version mismatches between quarkus-gradle-plugin and the Quarkus BOM where deployment artifact naming assumptions break.

Related errors

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/09e45294e6542df7. Report an issue: GitHub.