apache/beam · error

Params.MaxBufferingDuration must be >= 0; got %s

Error message

Params.MaxBufferingDuration must be >= 0; got %s

What it means

Params.MaxBufferingDuration was set to a negative duration, which is meaningless as a time window. validate() rejects it at pipeline-construction time so the transform never runs with an impossible configuration. Fix the Params struct before calling GroupIntoBatches.

Source

Thrown at sdks/go/pkg/beam/transforms/batch/batch.go:192

	// MaxBufferingDuration, when > 0, triggers emission of a partial
	// batch after this much processing time has elapsed since the
	// first element of the current batch was buffered.
	MaxBufferingDuration time.Duration
}

func (p Params) validate() error {
	if p.BatchSize < 0 {
		return fmt.Errorf("Params.BatchSize must be >= 0; got %d", p.BatchSize)
	}
	if p.BatchSizeBytes < 0 {
		return fmt.Errorf("Params.BatchSizeBytes must be >= 0; got %d", p.BatchSizeBytes)
	}
	if p.BatchSize == 0 && p.BatchSizeBytes == 0 {
		return fmt.Errorf("Params: at least one of BatchSize or BatchSizeBytes must be > 0")
	}
	if p.MaxBufferingDuration < 0 {
		return fmt.Errorf("Params.MaxBufferingDuration must be >= 0; got %s", p.MaxBufferingDuration)
	}
	return nil
}

const (
	sizerNone      int32 = 0
	sizerPrimitive int32 = 1
)

// codecCache keeps a per-value-type ElementEncoder/Decoder pair.
type codecCache struct {
	once sync.Once
	enc  beam.ElementEncoder
	dec  beam.ElementDecoder
}

func (c *codecCache) init(t reflect.Type) {
	c.once.Do(func() {

View on GitHub (pinned to 12126d8942)

Solutions

1. Print the Params value and find where MaxBufferingDuration becomes negative
2. Correct the config/arithmetic producing the negative duration, or clamp with time.Duration(0) minimum
3. Call params.validate() yourself before building the pipeline to fail fast
4. Remove MaxBufferingDuration (leave it 0) if buffering-time limiting is not needed

Example fix

// before
p := batch.Params{BatchSize: 100, MaxBufferingDuration: -2 * time.Second}
// after
p := batch.Params{BatchSize: 100, MaxBufferingDuration: 2 * time.Second}

if p.MaxBufferingDuration < 0 { return fmt.Errorf("bad MaxBufferingDuration: %s", p.MaxBufferingDuration) }
return p.validate()

When it happens

Trigger: Passing Params with MaxBufferingDuration set to a negative time.Duration (e.g. -5*time.Second) to GroupIntoBatches or GroupIntoBatchesWithShardedKey, which calls params.validate().

Common situations: Computing a duration from a signed config value or arithmetic that can go negative (e.g. deadline - now after the deadline passed), or typo signs when writing literals like -time.Second.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• empty pipeline
• OnTimer function is defined for the DoFn but no TimerProvide
• create has no values
• invalid scope
• invalid scope

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/ca329626536a3b8c. Report an issue: GitHub.