hasura/graphql-engine · error · ScalarBooleanExpressionTypeError

scalar type representation required for type {scalar_type:}

Error message

scalar type representation required for type {scalar_type:} in data connector {data_connector:}

What it means

A boolean expression operator requires a specific scalar type representation from the data connector (e.g. for equality/comparison arguments), but that scalar type is absent from the connector's scalar representations.

Source

Thrown at v3/crates/metadata-resolve/src/stages/scalar_boolean_expressions/error.rs:41

        scalar_type: DataConnectorScalarType,
    },
    #[error(
        "cannot find type {custom_type:} when resolving arguments for comparison operator {operator_name:} for {boolean_expression_type:}"
    )]
    UnknownCustomTypeInComparisonOperatorArgument {
        custom_type: Qualified<CustomTypeName>,
        operator_name: OperatorName,
        boolean_expression_type: Qualified<CustomTypeName>,
    },
    #[error("data connector {data_connector:} could not be found")]
    DataConnectorNotFound {
        data_connector: Qualified<DataConnectorName>,
    },
    #[error("scalar representations for data connector {data_connector:} could not be found")]
    DataConnectorScalarRepresentationsNotFound {
        data_connector: Qualified<DataConnectorName>,
    },
    #[error(
        "scalar type representation required for type {scalar_type:} in data connector {data_connector:}"
    )]
    DataConnectorScalarRepresentationRequired {
        data_connector: Qualified<DataConnectorName>,
        scalar_type: DataConnectorScalarType,
    },
    #[error("Predicate types in data connectors are unsupported")]
    PredicateTypesUnsupported,
    #[error("{0}")]
    GraphqlError(#[from] graphql_config::GraphqlConfigError),
}

impl ContextualError for ScalarBooleanExpressionTypeError {
    fn create_error_context(&self) -> Option<error_context::Context> {
        None
    }
}

View on GitHub (pinned to 724551b9ae)

Solutions

1. Confirm the connector actually supports the scalar type referenced by the operator
2. Refresh the connector's capabilities/schema so newly added scalar types appear
3. Remove or remap the operator to a supported scalar type

// check required scalar type exists in connector representations
let scalars: HashSet<_> = caps.scalar_types.keys().cloned().collect();
for op in &required_operators {
    if !scalars.contains(&op.scalar_type) { return Err(format!("missing scalar: {}", op.scalar_type)); }
}

When it happens

Trigger: An operator on a boolean expression type is used against a scalar whose DataConnectorScalarType is not present in the connector's reported scalar type representations.

Common situations: Connector does not support the scalar type used by the operator (e.g. a custom scalar), capabilities out of date after the connector added new types, or mapping an operator to a type the connector never exports.

Related errors

• the operand type '{operand_type}' must be a scalar type
• Scalar representations for data connector '{data_connector_n
• Model {model:} has source data connector object type {model_
• the aggregate expression '{aggregate_expression}' is used wi
• data connector {data_connector:} could not be found

AI-assisted analysis of hasura/graphql-engine@724551b9ae (2026-08-28). Data as JSON: /api/errors/b9c42840d021fe63. Report an issue: GitHub.