apache/beam · error · GradleException

Javadoc not generated. Check logs for errors

Error message

Javadoc not generated. Check logs for errors

What it means

Beam's javadoc Gradle task sets failOnError=false so warnings do not break the build, but afterwards it checks whether docs/javadoc/index.html was produced. If the Javadoc tool failed hard enough that no index.html exists, the build throws this GradleException.

Solutions

1. Rerun the task and inspect the build logs above the failure for the actual javadoc errors.
2. Fix the reported Javadoc issues (broken @link/@param tags, missing comments, unresolvable references).
3. Run with --info or --debug to see the exact javadoc command output if the log is not clear.

./gradlew :sdks:java:javadoc:javadoc --info | grep -i 'error\|warning'

When it happens

Trigger: Running `./gradlew :sdks:java:javadoc:javadoc` when the javadoc tool exits with errors (bad doc comments, broken links, missing sources) so severe that no output index.html is generated.

Common situations: Adding a new class with malformed Javadoc tags or invalid {@link} references; JDK version change making previously tolerated doc errors fatal; missing dependencies on the javadoc classpath.

Understand the failure class

Background: "File not found" and ENOENT errors: why libraries can't find a file that should exist — this error's family across 50 libraries.

Related errors

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• error occurred
• Unknown yamlTestSet: . Must be one of 'data', 'databases'…
• cannot pull dev versions of JARs, please run "gradlew
• Could not find in

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/2f08f82545d21d0f. Report an issue: GitHub.

Appendix: source

Thrown at sdks/java/javadoc/build.gradle:99

      links createJavadocIOUrlForDependency(dep)
    }
  }

  // certain projects need generated sources for javadoc generation
  // Part of flink sources came from custom copySourceOverrides target
  dependsOn ":runners:flink:${flink_versions.split(",").first()}:copySourceOverrides"
  // Auto value class appeared in class annotation (jackson)
  dependsOn ':sdks:java:io:solace:compileJava'
  source project(':sdks:java:io:solace').layout.buildDirectory.dir('generated/sources/annotationProcessor/java/main')
  dependsOn ':sdks:java:io:amazon-web-services2:compileJava'
  source project(':sdks:java:io:amazon-web-services2').layout.buildDirectory.dir('generated/sources/annotationProcessor/java/main')

  doLast {
    File myFile = new File(layout.buildDirectory.dir("docs/javadoc/index.html").get().toString())

    // Because we set failOnError false, Check if the doc successfully generated
    if (!myFile.exists()) {
      throw new GradleException("Javadoc not generated. Check logs for errors")
    }
  }
}

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