weaviate/weaviate · error

read class name length: %w

Error message

read class name length: %w

What it means

Raised by fromBinaryOptionalInternal in entities/storobj/storage_object.go:273 when rw.ReadUint16Checked() fails reading the on-disk class-name length field — the buffer ends before the uint16 can be read. This check happens after the vector section, so failing here indicates truncation of the payload past the vector region. Note: if className is supplied non-empty (Disk variant), a corrupt length still aborts decode even though the value would have been skipped.

Source

Thrown at entities/storobj/storage_object.go:273

		}
		ko.Object.Vector = make([]float32, vectorLength)
		byteops.CopyBytesToSlice(ko.Object.Vector, vectorBytes)
	} else {
		if err := rw.SkipChecked(vectorByteLen); err != nil {
			return nil, fmt.Errorf("skip vector: %w", err)
		}
		ko.Object.Vector = nil
	}
	ko.Vector = ko.Object.Vector

	// className precedence: a non-empty caller-supplied className wins and
	// the on-disk class-name bytes are skipped. An empty caller className
	// falls back to the on-disk value. If both are empty there is no class
	// to attach to the decoded object — return an error rather than produce
	// a silent empty Class.
	classNameLength, err := rw.ReadUint16Checked()
	if err != nil {
		return nil, fmt.Errorf("read class name length: %w", err)
	}
	if className == "" {
		if classNameLength == 0 {
			return nil, errors.New("storobj: cannot decode object with empty className: caller supplied no className and on-disk class-name field is empty")
		}
		classNameBytes, err := rw.ReadBytesFromBufferChecked(uint64(classNameLength))
		if err != nil {
			return nil, fmt.Errorf("read class name: %w", err)
		}
		className = string(classNameBytes)
	} else if err := rw.SkipChecked(uint64(classNameLength)); err != nil {
		return nil, fmt.Errorf("skip class name: %w", err)
	}

	propLength, err := rw.ReadUint32Checked()
	if err != nil {
		return nil, fmt.Errorf("read properties length: %w", err)
	}

View on GitHub (pinned to 75aa4b6d11)

Solutions

1. Re-fetch the object; if persistent, restore from backup or a healthy replica.
2. Verify the payload slice is complete and starts at the object boundary (no offset misalignment).
3. Confirm marshaller version byte is 1 on both writer and reader.
4. If widespread across objects, check segment-file integrity for the shard.

obj, err := storobj.FromBinaryOptionalDisk(data, className, addProps, extraction)
if err != nil {
    logger.Warnf("decode of %s failed past vector section: %v", className, err)
    return nil
}

When it happens

Trigger: FromBinaryOptionalNetwork / FromBinaryOptionalDisk called with a payload that ends immediately after the vector section, so the uint16 class-name length cannot be read.

Common situations: Truncated network transfer or disk read; corrupted LSM value cut between the vector and class-name fields; caller passing a wrong-format or partially sliced blob.

Related errors

• read class name: %w
• skip class name: %w
• read vector length: %w
• read vector: %w
• skip vector: %w

AI-assisted analysis of weaviate/weaviate@75aa4b6d11 (2026-09-04). Data as JSON: /api/errors/205ee0495638ab7b. Report an issue: GitHub.