apache/beam · error

coder with id not found

Error message

coder with id %v not found

What it means

CoderUnmarshaller.Coder looks up a coder by ID first in the already-unmarshaled coders map, then in the raw model map from the pipeline proto. If the ID is in neither, it throws "coder with id %v not found" wrapped with context 'unmarshalling coder <id>'. It means the pipeline graph references a coder that was never (or no longer) included in the coder definitions.

Solutions

1. Check the coder ID in the error exists in the pipeline proto's components.coders map; re-marshal the pipeline if it was hand-built.
2. Regenerate the pipeline with the same Beam SDK version as the runner to avoid dropped/mismatched coders.
3. If constructing the pipeline programmatically, ensure every PCollection's coder is registered before unmarshaling.
4. Upgrade or align beam Go SDK versions between job submission and runner/stager.

// Before unmarshaling, verify referenced coder IDs exist:
for id, pc := range comps.GetPcollections() {
    if _, ok := comps.GetCoders()[pc.GetCoderId()]; !ok {
        return fmt.Errorf("pcollection %s references missing coder %s", id, pc.GetCoderId())
    }
}

c, err := um.Coder(id)
if err != nil && strings.Contains(err.Error(), "not found") {
    log.Printf("missing coder %q in pipeline proto: %v", id, err)
}

When it happens

Trigger: Unmarshaling a pipeline whose components reference a coder ID absent from pipepb components' coders map — via UnmarshalCoders, makeCoderForPCollection, or makeLink during pipeline deserialization.

Common situations: A partially constructed or hand-edited pipeline proto; a runner/SDK version mismatch dropping coder definitions; a serialized pipeline (e.g. saved model) truncated or produced by an older SDK that pruned coders.

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

• array len mismatch. decoding
• bad coder kind
• bad decoding function
• bad encoding function
• bad input kind

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/dd5b7ed69bfc9a96. Report an issue: GitHub.

Appendix: source

Thrown at sdks/go/pkg/beam/core/runtime/graphx/coder.go:145

	coders := make([]*coder.Coder, len(ids))
	for i, id := range ids {
		c, err := b.Coder(id)
		if err != nil {
			return nil, err
		}
		coders[i] = c
	}
	return coders, nil
}

// Coder unmarshals a coder with the given id.
func (b *CoderUnmarshaller) Coder(id string) (*coder.Coder, error) {
	if c, exists := b.coders[id]; exists {
		return c, nil
	}
	c, ok := b.models[id]
	if !ok {
		err := errors.Errorf("coder with id %v not found", id)
		return nil, errors.WithContextf(err, "unmarshalling coder %v", id)
	}

	ret, err := b.makeCoder(id, c)
	if err != nil {
		return nil, errors.WithContextf(err, "unmarshalling coder %v", id)
	}
	ret.ID = id

	b.coders[id] = ret
	return ret, nil
}

// WindowCoder unmarshals a window coder with the given id.
func (b *CoderUnmarshaller) WindowCoder(id string) (*coder.WindowCoder, error) {
	if w, exists := b.windowCoders[id]; exists {
		return w, nil
	}

View on GitHub (pinned to 12126d8942)