dbt-labs/dbt-core · error

invalid serialized timestamp precision

Error message

invalid serialized timestamp precision

What it means

Panic from `parse::<u8>().expect("invalid serialized timestamp precision")` in `is_timestamp_ntz`. Field names encoded as `timestamp_ntz:<u8>` must carry a numeric precision suffix that fits u8 and TimePrecision's constraints; a non-numeric, empty, or out-of-range suffix makes the parse fail and panics.

Source

Thrown at crates/dbt-adapter/src/sql_types.rs:1085

                        .expect("string prefix checked")
                        .parse::<u8>()
                        .expect("invalid serialized time precision"),
                ))
            }
            _ => IsTimestamp::No,
        }
    }

    pub fn is_timestamp_ntz(data_type: &DataType) -> IsTimestamp {
        match data_type {
            DataType::FixedSizeList(field, 1) if field.name().starts_with("timestamp_ntz:") => {
                IsTimestamp::Yes(TimePrecision::new(
                    field
                        .name()
                        .strip_prefix("timestamp_ntz:")
                        .expect("string prefix checked")
                        .parse::<u8>()
                        .expect("invalid serialized timestamp precision"),
                ))
            }
            _ => IsTimestamp::No,
        }
    }

    pub fn is_timestamp_ltz(data_type: &DataType) -> IsTimestamp {
        match data_type {
            DataType::FixedSizeList(field, 1) if field.name().starts_with("timestamp_ltz:") => {
                IsTimestamp::Yes(TimePrecision::new(
                    field
                        .name()
                        .strip_prefix("timestamp_ltz:")
                        .expect("string prefix checked")
                        .parse::<u8>()
                        .expect("invalid serialized timestamp precision"),
                ))
            }

View on GitHub (pinned to 0267ce9170)

Solutions

1. Correct the field name to a valid precision (e.g. `timestamp_ntz:6` for microseconds) at the serialization site.
2. Regenerate stale recordings/fixtures with the current serializer rather than editing field names manually.
3. Check for version drift between the component that wrote the schema and the one reading it; align the encoding format.
4. Harden the reader: map parse failure to a proper error or IsTimestamp::No with a log instead of panicking.

Example fix

// before
.parse::<u8>()
.expect("invalid serialized timestamp precision"),
// after
.parse::<u8>().map_err(|_| panic!(
    "invalid serialized timestamp precision in '{}'", field.name())).unwrap(),

fn validate_ntz_precision(name: &str) -> Result<u8, String> {
    name.strip_prefix("timestamp_ntz:")
        .ok_or_else(|| format!("not an ntz field: {name}"))?
        .parse::<u8>()
        .map_err(|e| format!("bad ntz precision in '{name}': {e}"))
}

fn well_formed_ntz_type(dt: &DataType) -> bool {
    matches!(dt, DataType::FixedSizeList(f, 1)
        if f.name().strip_prefix("timestamp_ntz:").is_some_and(|s| s.parse::<u8>().is_ok()))
}

let checked = std::panic::catch_unwind(|| is_timestamp_ntz(&data_type));
match checked {
    Ok(ts) => use_timestamp(ts),
    Err(_) => log::error!("malformed timestamp_ntz field name in schema"),
}

When it happens

Trigger: Calling `is_timestamp_ntz` with a FixedSizeList(1) whose field name is like `timestamp_ntz:abc`, `timestamp_ntz:`, `timestamp_ntz:256`, or `timestamp_ntz:3.0` — i.e. malformed serialized NTZ timestamp metadata.

Common situations: Corrupted or hand-edited Arrow schema fixtures, recordings produced by a mismatched dbt/adapter version, typo when constructing synthetic schemas for Snowflake NTZ columns in tests.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

• invalid serialized time precision
• string prefix checked
• Schema not found for canonical FQN: {}
• `EnterGuard` values dropped out of order. Guards returned by
• {e} {:?}

AI-assisted analysis of dbt-labs/dbt-core@0267ce9170 (2026-09-07). Data as JSON: /api/errors/51e37b73e4e104d2. Report an issue: GitHub.