jackc/pgx · error

While generating load types query

Error message

While generating load types query: %w

What it means

Conn.LoadTypes failed while executing the catalog query built from the requested type names. The %w wraps the Query error itself (connection failure, SQL error, etc.). Note the message text is slightly misleading — it fires on query execution, not on SQL string construction.

Solutions

1. Unwrap to inspect the underlying query error
2. Verify the connection is alive and the type names are valid SQL identifiers
3. Check server logs for the corresponding failed query

When it happens

Trigger: Thrown at derived_types.go:181 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of jackc/pgx@ec1a0befd2 (2026-08-04). Data as JSON: /api/errors/71a74c17ef0c5810. Report an issue: GitHub.

Appendix: source

Thrown at derived_types.go:181

}

// LoadTypes performs a single (complex) query, returning all the required
// information to register the named types, as well as any other types directly
// or indirectly required to complete the registration.
// The result of this call can be passed into RegisterTypes to complete the process.
func (c *Conn) LoadTypes(ctx context.Context, typeNames []string) ([]*pgtype.Type, error) {
	m := c.TypeMap()
	if len(typeNames) == 0 {
		return nil, fmt.Errorf("No type names were supplied.")
	}

	// Disregard server version errors. This will result in
	// the SQL not support recent structures such as multirange
	serverVersion, _ := serverVersion(c)
	sql := buildLoadDerivedTypesSQL(serverVersion, typeNames)
	rows, err := c.Query(ctx, sql, QueryResultFormats{TextFormatCode}, typeNames)
	if err != nil {
		return nil, fmt.Errorf("While generating load types query: %w", err)
	}
	defer rows.Close()
	result := make([]*pgtype.Type, 0, 100)
	for rows.Next() {
		ti := derivedTypeInfo{}
		err = rows.Scan(&ti.TypeName, &ti.NspName, &ti.Typtype, &ti.Typbasetype, &ti.Typelem, &ti.Oid, &ti.Rngtypid, &ti.Rngsubtype, &ti.Attnames, &ti.Atttypids)
		if err != nil {
			return nil, fmt.Errorf("While scanning type information: %w", err)
		}
		var type_ *pgtype.Type
		switch ti.Typtype {
		case "b": // array
			dt, ok := m.TypeForOID(ti.Typelem)
			if !ok {
				return nil, fmt.Errorf("Array element OID %v not registered while loading pgtype %q", ti.Typelem, ti.TypeName)
			}
			type_ = &pgtype.Type{Name: ti.TypeName, OID: ti.Oid, Codec: &pgtype.ArrayCodec{ElementType: dt}}
		case "c": // composite

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