quickwit-oss/quickwit · error

custom fields are not supported in Quickwit

Error message

custom fields are not supported in Quickwit

What it means

Tantivy supports a `Custom` field type, but Quickwit's mapping deserializer does not implement it. Any mapping that resolves to tantivy's Type::Custom is rejected with this message rather than silently ignored, since Quickwit cannot map, index, or search such fields.

Source

Thrown at quickwit/quickwit-doc-mapper/src/doc_mapper/field_mapping_entry.rs:775

        }
        Type::F64 => {
            let numeric_options: QuickwitNumericOptions = serde_json::from_value(json)?;
            Ok(FieldMappingType::F64(numeric_options, cardinality))
        }
        Type::Bool => {
            let bool_options: QuickwitBoolOptions = serde_json::from_value(json)?;
            Ok(FieldMappingType::Bool(bool_options, cardinality))
        }
        Type::IpAddr => {
            let ip_addr_options: QuickwitIpAddrOptions = serde_json::from_value(json)?;
            Ok(FieldMappingType::IpAddr(ip_addr_options, cardinality))
        }
        Type::Date => {
            let date_time_options = serde_json::from_value::<QuickwitDateTimeOptions>(json)?;
            Ok(FieldMappingType::DateTime(date_time_options, cardinality))
        }
        Type::Facet => unimplemented!("Facet are not supported in quickwit yet."),
        Type::Custom => bail!("custom fields are not supported in Quickwit"),
        Type::Bytes => {
            let numeric_options: QuickwitBytesOptions = serde_json::from_value(json)?;
            if numeric_options.fast && cardinality == Cardinality::MultiValued {
                bail!("fast field is not allowed for array<bytes>");
            }
            Ok(FieldMappingType::Bytes(numeric_options, cardinality))
        }
        Type::Json => {
            let json_options: QuickwitJsonOptions = serde_json::from_value(json)?;
            Ok(FieldMappingType::Json(json_options, cardinality))
        }
    }
}

impl TryFrom<FieldMappingEntryForSerialization> for FieldMappingEntry {
    type Error = String;

    fn try_from(value: FieldMappingEntryForSerialization) -> Result<Self, String> {

View on GitHub (pinned to a39730c5cd)

Solutions

1. Use one of Quickwit's supported field types (text, json, u64, i64, f64, bool, date, bytes, object, concatenate) instead.
2. Remove the custom-typed field from the mapping.
3. If you need that capability, check whether a newer Quickwit version supports the corresponding type.

const SUPPORTED: &[&str] = &["text", "json", "u64", "i64", "f64", "bool", "date", "bytes", "object", "concatenate"];
fn field_type_supported(f: &serde_json::Value) -> bool {
    let t = f.get("type").and_then(|t| t.as_str()).unwrap_or("");
    SUPPORTED.contains(&t) || t.starts_with("array<") && SUPPORTED.contains(&t.trim_start_matches("array<").trim_end_matches('>'))
}

When it happens

Trigger: Deserializing a FieldMappingType whose field type string maps to Type::Custom in the from_json match — practically only reachable if a type alias resolves to the custom variant; ordinary users cannot select it.

Common situations: Forward-porting mappings from other tantivy-based tools that use custom field types; hand-editing serialized schema JSON; future tantivy types surfacing as Custom in older Quickwit versions.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• `record`, `tokenizer`, and `fieldnorms` parameters are allow
• `record` and `tokenizer` parameters are allowed only if inde
• object type must have at least one field mapping
• concatenate type must have at least one sub-field
• fast field is not allowed for array<bytes>

AI-assisted analysis of quickwit-oss/quickwit@a39730c5cd (2026-09-08). Data as JSON: /api/errors/273435355e569928. Report an issue: GitHub.