huggingface/candle · error

not a vec {v:?}

Error message

not a vec {v:?}

What it means

Value::to_vec throws this when the metadata value is not an Array. Only Value::Array variants can be borrowed as a list of nested values; scalar or string values bail with this message, printing the actual variant. It signals you tried to iterate a non-list GGUF entry.

Source

Thrown at candle-core/src/quantized/gguf_file.rs:308

    pub fn to_f64(&self) -> Result<f64> {
        match self {
            Self::F64(v) => Ok(*v),
            v => crate::bail!("not a f64 {v:?}"),
        }
    }

    pub fn to_bool(&self) -> Result<bool> {
        match self {
            Self::Bool(v) => Ok(*v),
            v => crate::bail!("not a bool {v:?}"),
        }
    }

    pub fn to_vec(&self) -> Result<&Vec<Value>> {
        match self {
            Self::Array(v) => Ok(v),
            v => crate::bail!("not a vec {v:?}"),
        }
    }

    pub fn to_string(&self) -> Result<&String> {
        match self {
            Self::String(v) => Ok(v),
            v => crate::bail!("not a string {v:?}"),
        }
    }

    fn read<R: std::io::Read + std::io::Seek>(
        reader: &mut R,
        value_type: ValueType,
        magic: &VersionedMagic,
        depth: usize,
        file_size: u64,
    ) -> Result<Self> {
        if depth > GGUF_MAX_VALUE_DEPTH {

View on GitHub (pinned to d5fee525bf)

Solutions

1. Call the accessor matching the printed variant (to_string for strings, to_u32 for numbers, ...).
2. Check the Content metadata map for the correct list key name (e.g. tokenizer.ggml.tokens vs tokenizer.ggml.model).
3. Match on Value::Array explicitly and skip/handle scalar entries when scanning all metadata.
4. Rewrite the GGUF file with the field as an Array if it was wrongly written as a scalar.

Example fix

// before
let tokens = content.metadata.get("tokenizer.ggml.tokens").unwrap().to_vec()?;
// after
let tokens = match content.metadata.get("tokenizer.ggml.tokens") {
    Some(gguf_file::Value::Array(vs)) => vs,
    Some(other) => candle_core::bail!("tokens is not an array: {other:?}"),
    None => candle_core::bail!("missing tokenizer.ggml.tokens"),
};

fn is_array(v: &gguf_file::Value) -> bool { matches!(v, gguf_file::Value::Array(_)) }
if !is_array(value) { bail!("expected array metadata, got {value:?}"); }

fn as_array(v: &gguf_file::Value) -> Option<&Vec<gguf_file::Value>> {
    if let gguf_file::Value::Array(vs) = v { Some(vs) } else { None }
}

let arr = match value.to_vec() {
    Ok(vs) => vs,
    Err(e) => { eprintln!("not an array: {e}"); return Ok(Vec::new()); }
};

When it happens

Trigger: Calling .to_vec() on a scalar metadata entry such as 'tokenizer.ggml.model' (a String) or a numeric field, when the intent was a list like 'tokenizer.ggml.tokens'.

Common situations: Confusing similarly named GGUF keys (singular vs .tokens/.scores/.merges plural forms); files where a list field was collapsed to a single scalar by the writer; iterating all Content metadata and assuming every value is an array.

Related errors

• not a f32 {v:?}
• not a f64 {v:?}
• not a bool {v:?}
• not a string {v:?}
• multiple value-types in the same array {value_type:?}

AI-assisted analysis of huggingface/candle@d5fee525bf (2026-09-02). Data as JSON: /api/errors/1f1395288513fc21. Report an issue: GitHub.