apache/beam · error

invalid status for combine %v: %v

Error message

invalid status for combine %v: %v

What it means

Combine.Up enforces the lifecycle state machine: the node must be in the Initializing status when Up is called. Calling Up on an already-initialized Combine (status Up, Active, etc.) indicates the bundle lifecycle methods are being invoked out of order or more than once.

Source

Thrown at sdks/go/pkg/beam/core/runtime/exec/combine.go:71

	aiValConvert func(any) any

	states *metrics.PTransformState
}

// GetPID returns the PTransformID for this CombineFn.
func (n *Combine) GetPID() string {
	return n.PID
}

// ID returns the UnitID for this node.
func (n *Combine) ID() UnitID {
	return n.UID
}

// Up initializes this CombineFn and runs its SetupFn() method.
func (n *Combine) Up(ctx context.Context) error {
	if n.status != Initializing {
		return errors.Errorf("invalid status for combine %v: %v", n.UID, n.status)
	}
	n.status = Up

	n.states = metrics.NewPTransformState(n.PID)

	if _, err := InvokeWithoutEventTime(ctx, n.Fn.SetupFn(), nil, nil, nil, nil, nil); err != nil {
		return n.fail(err)
	}

	if ca := n.Fn.CreateAccumulatorFn(); ca != nil {
		n.createAccumInv = newInvoker(ca)
	}
	if ai := n.Fn.AddInputFn(); ai != nil {
		n.addInputInv = newInvoker(ai)
	} else {
		n.optimizeMergeFn()
	}
	n.mergeInv = newInvoker(n.Fn.MergeAccumulatorsFn())

View on GitHub (pinned to 12126d8942)

Solutions

1. Call each lifecycle method exactly once and in order: Up, StartBundle, ProcessElement(s), FinishBundle.
2. Reset status to Initializing (construct a fresh Combine) before calling Up again.
3. Check for runner code paths that re-invoke Up on a shared plan instance.

// guard before calling Up
// Combine has no exported status field; drive lifecycle through plan.Execute instead of direct calls.

if err := combine.Up(ctx); err != nil {
	if strings.Contains(err.Error(), "invalid status for combine") {
		// the node was already initialized; rebuild the plan instead of re-upping
	}
	return err
}

When it happens

Trigger: Calling Up twice on the same Combine unit, or calling Up after StartBundle/FinishBundle without re-initialization.

Common situations: Custom runner code or tests building a plan and invoking lifecycle methods manually; runner bugs that re-up a cached plan without resetting node status.

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 extract %v: %v
• invalid status for combine convert %v: %v
• invalid status for pardo %v: %v, want Initializing

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/32e2be997e6257aa. Report an issue: GitHub.