hasura/graphql-engine · error · DataConnectorScalarTypesError::DuplicateDataConnectorScalarRepresentation

multiple type representations defined for scalar {scalar_typ

Error message

multiple type representations defined for scalar {scalar_type:} from data connector {data_connector:}

What it means

A data connector scalar type has multiple conflicting type representations defined in metadata. Only one representation per (connector, scalar) pair is allowed so the scalar's GraphQL/SQL mapping is unambiguous.

Source

Thrown at v3/crates/metadata-resolve/src/stages/data_connector_scalar_types/error.rs:18

use open_dds::types::CustomTypeName;

use open_dds::data_connector::{DataConnectorName, DataConnectorScalarType};

use crate::types::error::ContextualError;
use crate::types::subgraph::Qualified;

use crate::stages::{graphql_config, scalar_boolean_expressions};

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

#[derive(Debug, thiserror::Error)]
pub enum DataConnectorScalarTypesError {
    #[error(
        "multiple type representations defined for scalar {scalar_type:} from data connector {data_connector:}"
    )]
    DuplicateDataConnectorScalarRepresentation {
        data_connector: Qualified<DataConnectorName>,
        scalar_type: DataConnectorScalarType,
    },
    #[error("unknown type represented for scalar type {scalar_type:}: {type_name:}")]
    ScalarTypeUnknownRepresentation {
        scalar_type: DataConnectorScalarType,
        type_name: Qualified<CustomTypeName>,
    },
    #[error("{0}")]
    GraphqlConfigError(#[from] graphql_config::GraphqlConfigError),
    #[error("{0}")]
    ScalarBooleanExpressionTypeError(
        #[from] scalar_boolean_expressions::ScalarBooleanExpressionTypeError,
    ),
}

View on GitHub (pinned to 724551b9ae)

Solutions

1. Find duplicate scalar definitions for the connector
2. Keep exactly one representation and delete or merge the others
3. Rebuild metadata

// Key scalar representations by (connector, scalar) and assert no duplicates
let mut seen = HashSet::new();
for (conn, scalar, _repr) in reps { assert!(seen.insert((conn, scalar))); }

Catch DuplicateDataConnectorScalarRepresentation and report the connector/scalar pair.

When it happens

Trigger: Defining the same DataConnectorScalarType with more than one type representation under the same data connector.

Common situations: Merging metadata files that both define the same connector scalar with different representations; copy-paste of scalar blocks.

Related errors

• the data connector is defined more than once
• Data connector {data_connector_name} is referenced by multip
• unknown data connector {data_connector:} referenced in scala
• scalar representations for data connector {data_connector:}
• cannot get absolute path: %w

AI-assisted analysis of hasura/graphql-engine@724551b9ae (2026-08-28). Data as JSON: /api/errors/6b462ffb0b1fca78. Report an issue: GitHub.