GoogleContainerTools/skaffold · error

found a '%s' artifact, which is incompatible with the 'gcb'

Error message

found a '%s' artifact, which is incompatible with the 'gcb' builder:

%s

To use the '%s' builder, remove the 'googleCloudBuild' stanza from the 'build' section of your configuration. For information, see https://skaffold.dev/docs/pipeline-stages/builders/

What it means

Google Cloud Build (gcb) can only build kaniko, docker, jib, buildpack, and ko artifact types. Any other artifact type (e.g. custom, bazel, nixpacks) under a googleCloudBuild build stanza fails validation, with advice to remove the gcb stanza to use a builder that supports that type.

Source

Thrown at pkg/skaffold/schema/validation/validation.go:660

// validateArtifactTypes checks that the artifact types are compatible with the specified builder.
func validateArtifactTypes(cfg *parser.SkaffoldConfigEntry, bc latest.BuildConfig) []ErrorWithLocation {
	cfgErrs := []ErrorWithLocation{}
	switch {
	case bc.LocalBuild != nil:
		for i, a := range bc.Artifacts {
			if misc.ArtifactType(a) == misc.Kaniko {
				cfgErrs = append(cfgErrs, ErrorWithLocation{
					Error:    fmt.Errorf("found a '%s' artifact, which is incompatible with the 'local' builder:\n\n%s\n\nTo use the '%s' builder, add the 'cluster' stanza to the 'build' section of your configuration. For information, see https://skaffold.dev/docs/pipeline-stages/builders/", misc.ArtifactType(a), misc.FormatArtifact(a), misc.ArtifactType(a)),
					Location: cfg.YAMLInfos.Locate(&cfg.Build.Artifacts[i].ArtifactType),
				})
			}
		}
	case bc.GoogleCloudBuild != nil:
		for i, a := range bc.Artifacts {
			at := misc.ArtifactType(a)
			if at != misc.Kaniko && at != misc.Docker && at != misc.Jib && at != misc.Buildpack && at != misc.Ko {
				cfgErrs = append(cfgErrs, ErrorWithLocation{
					Error:    fmt.Errorf("found a '%s' artifact, which is incompatible with the 'gcb' builder:\n\n%s\n\nTo use the '%s' builder, remove the 'googleCloudBuild' stanza from the 'build' section of your configuration. For information, see https://skaffold.dev/docs/pipeline-stages/builders/", misc.ArtifactType(a), misc.FormatArtifact(a), misc.ArtifactType(a)),
					Location: cfg.YAMLInfos.Locate(&cfg.Build.Artifacts[i].ArtifactType),
				})
			}
		}
	case bc.Cluster != nil:
		for i, a := range bc.Artifacts {
			if misc.ArtifactType(a) != misc.Kaniko && misc.ArtifactType(a) != misc.Custom {
				cfgErrs = append(cfgErrs, ErrorWithLocation{
					Error:    fmt.Errorf("found a '%s' artifact, which is incompatible with the 'cluster' builder:\n\n%s\n\nTo use the '%s' builder, remove the 'cluster' stanza from the 'build' section of your configuration. For information, see https://skaffold.dev/docs/pipeline-stages/builders/", misc.ArtifactType(a), misc.FormatArtifact(a), misc.ArtifactType(a)),
					Location: cfg.YAMLInfos.Locate(&cfg.Build.Artifacts[i].ArtifactType),
				})
			}
		}
	}
	return cfgErrs
}

// validateGCBConfig checks if GCB config is valid.

View on GitHub (pinned to a1189de023)

Solutions

1. Remove the `googleCloudBuild` stanza and use `local:` or `cluster:` if the artifact type needs it
2. Convert the artifact to a supported type (docker/jib/buildpack/ko/kaniko)
3. Move the unsupported artifact to a separate profile with a compatible builder

Example fix

# before
build:
  googleCloudBuild:
    projectId: my-project
  artifacts:
    - image: myapp
      custom:
        buildCommand: ./build.sh
# after
build:
  local: {}
  artifacts:
    - image: myapp
      custom:
        buildCommand: ./build.sh

const gcbAllowed = ['kaniko','docker','jib','buildpack','ko'];
if (config.build?.googleCloudBuild && config.build.artifacts?.some(a => !gcbAllowed.some(t => a[t]))) {
  throw new Error('artifact type not supported by googleCloudBuild builder');
}

function gcbCompatible(cfg) {
  const ok = ['kaniko','docker','jib','buildpack','ko'];
  return !cfg?.build?.googleCloudBuild || cfg.build.artifacts?.every(a => ok.some(t => a[t]));
}

try {
  await skaffold.run(config);
} catch (e) {
  if (/incompatible with the 'gcb' builder/.test(e.message)) {
    console.error('Use a supported artifact type or switch builder stanza');
  } else throw e;
}

When it happens

Trigger: skaffold.yaml has `build.googleCloudBuild:` and an artifact whose type is not one of kaniko/docker/jib/buildpack/ko; validated in validateArtifactTypes.

Common situations: Using a `custom:` build script while submitting builds to Cloud Build, or leftover bazel artifacts from older configs.

Related errors

• invalid value for worker pool. Must match pattern projects/{
• verify command expects non-zero number of test cases
• CONFIG_MISSING_MANIFEST_FILE_ERR
• INIT_CLOUD_RUN_LOCATION_ERROR
• missing apiVersion

AI-assisted analysis of GoogleContainerTools/skaffold@a1189de023 (2026-09-05). Data as JSON: /api/errors/b96c729eb9539048. Report an issue: GitHub.