apache/beam · error

failed to add window strategy

Error message

failed to add window strategy %v

What it means

addWindowingStrategy marshals a window.WindowingStrategy into a pipepb.WindowingStrategy via MarshalWindowingStrategy. Any marshal failure (unsupported window kind, coder failure for the window, bad trigger) is wrapped as 'failed to add window strategy %v' before the default environment is attached and the strategy is interned.

Solutions

1. Inspect the wrapped error from MarshalWindowingStrategy for the specific unsupported component
2. Restrict pipelines to supported window kinds and standard triggers
3. If a custom WindowFn is required, translate it into one of the supported kinds before submitting
4. Upgrade/align the Go SDK version with the rest of the pipeline's SDKs

Example fix

null

// pre-check windowing strategy components before building pipeline
ws := n.WindowingStrategy()
if ws == nil || ws.Fn() == nil {
    return errors.New("missing windowing strategy")
}

if err := beam.Run(ctx, pr); err != nil {
    if strings.Contains(err.Error(), "failed to add window strategy") {
        return fmt.Errorf("windowing strategy not supported by Go marshaller: %w", err)
    }
    return err
}

When it happens

Trigger: A node with an unsupported windowing strategy reaches makeNode: non-standard window.Kind, a window coder that fails to construct, or trigger payloads that cannot be marshalled.

Common situations: Custom WindowFn implementations; windowing strategies carried across language boundaries that the Go marshaller cannot express; SDK version drift introducing unmarshalable window settings.

Related errors

• failed to add input kind
• failed to make node with node id
• AfterProcessingTime trigger set without a delay or…
• array len mismatch. decoding
• At least one subtrigger required for composite triggers.

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/1c61b82309d1f89d. Report an issue: GitHub.

Appendix: source

Thrown at sdks/go/pkg/beam/core/runtime/graphx/translate.go:1225

	if _, exists := m.environments[defaultEnvId]; !exists {
		env := proto.Clone(m.opt.Environment).(*pipepb.Environment)
		// If there's no environment set, we need to ignore
		if env == nil {
			return defaultEnvId
		}
		// Add the pipeline level resource hints here for now.
		// TODO(https://github.com/apache/beam/issues/23893) move to a better place for
		// scoped hints in next pass, which affect number of environments set by Go pipelines.
		env.ResourceHints = m.opt.PipelineResourceHints.Payloads()
		m.environments[defaultEnvId] = env
	}
	return defaultEnvId
}

func (m *marshaller) addWindowingStrategy(w *window.WindowingStrategy) (string, error) {
	ws, err := MarshalWindowingStrategy(m.coders, w)
	if err != nil {
		return "", errors.Wrapf(err, "failed to add window strategy %v", w)
	}
	ws.EnvironmentId = m.addDefaultEnv()
	return m.internWindowingStrategy(ws), nil
}

func (m *marshaller) internWindowingStrategy(w *pipepb.WindowingStrategy) string {
	key := w.String()
	if id, exists := m.windowing2id[(key)]; exists {
		return id
	}

	id := fmt.Sprintf("w%v", len(m.windowing2id))
	m.windowing2id[string(key)] = id
	m.windowing[id] = w
	return id
}

// MarshalWindowingStrategy marshals the given windowing strategy in

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