apache/beam · error

invalid status for combine extract %v: %v

Error message

invalid status for combine extract %v: %v

What it means

ExtractOutput.ProcessElement (which extracts final results from accumulators) requires the node to be Active inside a started bundle. Any other status means ProcessElement was called outside the expected lifecycle phase.

Source

Thrown at sdks/go/pkg/beam/core/runtime/exec/combine.go:633

		return err
	}
	n.optimizeMergeFn()
	return nil
}

// ExtractOutput is an executor for extracting output from a lifted combine.
type ExtractOutput struct {
	*Combine
}

func (n *ExtractOutput) String() string {
	return fmt.Sprintf("ExtractOutput[%v] Keyed:%v Out:%v", path.Base(n.Fn.Name()), n.UsesKey, n.Out.ID())
}

// ProcessElement accepts an accumulator value, and extracts the final return type from it.
func (n *ExtractOutput) ProcessElement(ctx context.Context, value *FullValue, values ...ReStream) error {
	if n.status != Active {
		return errors.Errorf("invalid status for combine extract %v: %v", n.UID, n.status)
	}
	n.Combine.states.Set(n.Combine.ctx, metrics.StartBundle)
	out, err := n.extract(n.Combine.ctx, value.Elm2)
	if err != nil {
		return n.fail(err)
	}
	return n.Out.ProcessElement(n.Combine.ctx, &FullValue{Windows: value.Windows, Elm: value.Elm, Elm2: out, Timestamp: value.Timestamp})
}

// ConvertToAccumulators is an executor for converting an input value to an accumulator value.
type ConvertToAccumulators struct {
	*Combine
}

func (n *ConvertToAccumulators) String() string {
	return fmt.Sprintf("ConvertToAccumulators[%v] Keyed:%v Out:%v", path.Base(n.Fn.Name()), n.UsesKey, n.Out.ID())
}

View on GitHub (pinned to 12126d8942)

Solutions

1. Drive the lifecycle: Up, StartBundle, ProcessElement, FinishBundle.
2. Verify StartBundle returned nil error before emitting accumulator values.
3. Construct a fresh ExtractOutput node if reuse across bundles is needed without proper state resets.

if err := extract.ProcessElement(ctx, fv, values); err != nil {
	if strings.Contains(err.Error(), "invalid status for combine extract") {
		// ensure extract node is inside an active bundle
	}
	return err
}

When it happens

Trigger: Calling ExtractOutput.ProcessElement before StartBundle or after FinishBundle.

Common situations: Direct unit invocation in tests; runner bugs where extraction is triggered outside bundle execution.

Understand the failure class

Background: "Invalid state transition" errors: "status must be X, actually Y", "already rejected/charging/uninstalled", "cannot ... while running" — what they mean when a library rejects your call — this error's family across 31 libraries.

Related errors

• invalid status for precombine %v: %v
• invalid status for combine merge %v: %v
• invalid status for combine convert %v: %v
• invalid status for combine %v: %v
• unable to infer CombineFn accumulator coder

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/ed328a3c90b4b29a. Report an issue: GitHub.