Tencent/WeKnora · error

empty embedding vector for chunk ID: %s

Error message

empty embedding vector for chunk ID: %s

What it means

Elasticsearch v8 save guard: the converted embedding document for the chunk carries a zero-length vector, meaning the chunk was indexed without an embedding (embedding failure upstream or unsupported content), and the save is rejected because ES cannot index an empty dense vector.

Source

Thrown at internal/application/repository/retriever/elasticsearch/v8/repository.go:167

	logger.GetLogger(ctx).Infof(
		"[Elasticsearch] Storage size for %d indices: %d bytes", len(indexInfoList), totalStorageSize,
	)
	return totalStorageSize
}

// Save stores a single index document in Elasticsearch
// Returns an error if the operation fails
func (e *elasticsearchRepository) Save(ctx context.Context,
	embedding *typesLocal.IndexInfo,
	additionalParams map[string]any,
) error {
	log := logger.GetLogger(ctx)
	log.Debugf("[Elasticsearch] Saving index for chunk ID: %s", embedding.ChunkID)

	// Convert to database format
	embeddingDB := elasticsearchRetriever.ToDBVectorEmbedding(embedding, additionalParams)
	if len(embeddingDB.Embedding) == 0 {
		err := fmt.Errorf("empty embedding vector for chunk ID: %s", embedding.ChunkID)
		log.Errorf("[Elasticsearch] %v", err)
		return err
	}

	// Index the document
	resp, err := e.client.Index(e.index).Request(embeddingDB).Do(ctx)
	if err != nil {
		log.Errorf("[Elasticsearch] Failed to save index: %v", err)
		return err
	}

	log.Infof("[Elasticsearch] Successfully saved index for chunk ID: %s, document ID: %s", embedding.ChunkID, resp.Id_)
	return nil
}

// BatchSave stores multiple index documents in Elasticsearch using bulk API
// Returns an error if the operation fails
func (e *elasticsearchRepository) BatchSave(ctx context.Context,

View on GitHub (pinned to 988cbb0330)

Solutions

1. Verify the embedding pipeline produced a vector for this chunk
2. Skip non-embeddable chunks instead of saving them
3. Check embedding dimension/model configuration

When it happens

Trigger: Thrown at internal/application/repository/retriever/elasticsearch/v8/repository.go:167 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of Tencent/WeKnora@988cbb0330 (2026-09-02). Data as JSON: /api/errors/875fba51d09638e8. Report an issue: GitHub.