What causes "Obtaining project build output files failed" in GoogleContainerTools/jib?

Run the jar (or bootJar) task before Jib, or make Jib tasks depend on it (tasks.named('jib') { dependsOn tasks.named('jar') })

GoogleContainerTools/jib · error · GradleException

Obtaining project build output files failed

Error message

Obtaining project build output files failed

What it means

createJibContainerBuilder wraps any IOException from collecting the project's build output files (JAR/WAR resolution, dependency scanning) in a GradleException with the fixed message 'Obtaining project build output files failed'. It signals that Jib could not read the files it needs to package into the container, not a config parse problem.

Source

Thrown at jib-gradle-plugin/src/main/java/com/google/cloud/tools/jib/gradle/GradleProjectProperties.java:285

          }
          break;

        case PACKAGED:
          // Add a JAR
          Jar jarTask = (Jar) project.getTasks().findByName("jar");
          Path jarPath = jarTask.getArchiveFile().get().getAsFile().toPath();
          log(LogEvent.debug("Using JAR: " + jarPath));
          javaContainerBuilder.addToClasspath(jarPath);
          break;

        default:
          throw new IllegalStateException("unknown containerizing mode: " + containerizingMode);
      }

      return javaContainerBuilder.toContainerBuilder();

    } catch (IOException ex) {
      throw new GradleException("Obtaining project build output files failed", ex);
    }
  }

  @Override
  public List<Path> getClassFiles() throws IOException {
    // TODO: Consolidate with createJibContainerBuilder
    FileCollection classesOutputDirectories =
        getMainSourceSet().getOutput().getClassesDirs().filter(File::exists);
    List<Path> classFiles = new ArrayList<>();
    for (File classesOutputDirectory : classesOutputDirectories) {
      classFiles.addAll(new DirectoryWalker(classesOutputDirectory.toPath()).walk());
    }
    return classFiles;
  }

  @Override
  public List<Path> getDependencies() {
    List<Path> dependencies = new ArrayList<>();

View on GitHub (pinned to fb949e2676)

Solutions

Run the jar (or bootJar) task before Jib, or make Jib tasks depend on it (tasks.named('jib') { dependsOn tasks.named('jar') })
Verify the jar task output exists under build/libs and the archiveFileName configuration is valid
Check filesystem permissions and re-run with --refresh-dependencies if dependency resolution is failing

Example fix

// before: invoking jib directly after clean with no jar dependency
// after
tasks.named('jibBuildTar') { dependsOn tasks.named('jar') }

Defensive patterns

Strategy: try-catch

Validate before calling

tasks.named('jibBuildTar') { dependsOn tasks.named('jar') } // or bootJar
assert tasks.named('jar').get().archiveFile.get().asFile.exists()

Try / catch

try {
  /* jib task */
} catch (GradleException e) {
  if (e.message == 'Obtaining project build output files failed') {
    logger.error('Run the jar/bootJar task first; check build/libs output exists')
  } else throw e
}

Prevention

Always build the jar/bootJar before Jib packaging tasks
Do not rename or relocate the jar task's output directory without updating Jib configuration
Check file permissions on the build directory in CI containers

When it happens

Trigger: An IOException while resolving jarTask.getArchiveFile() (task not produced output), reading the classes/dependencies directories, or scanning project artifacts during createJibContainerBuilder.

Common situations: Running jib tasks without first running the jar/bootJar build (missing output); jar task relocated/renamed so archiveFile points to nothing readable; filesystem permissions or missing build directory after clean in CI.

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

AI-assisted analysis of GoogleContainerTools/jib@fb949e2676 (2026-09-06). Data as JSON: /api/errors/296454a525c6ee65. Report an issue: GitHub.