apache/flink · error · InvalidFieldReferenceException

Invalid format of tuple field expression "{}".

Error message

Invalid format of tuple field expression "{}".

What it means

Thrown by TupleTypeInfoBase.getTypeAt(String) when the field expression does not match PATTERN_NESTED_FIELDS. The expected format is an integer with optional 'f' prefix (e.g. '0', 'f0', 'f2'), optionally followed by a dot and a nested expression (e.g. 'f0.name'). Any string that deviates from this pattern (and is not a wildcard) triggers this error.

Source

Thrown at flink-core/src/main/java/org/apache/flink/api/java/typeutils/TupleTypeInfoBase.java:194

                                    + "\" not possible on atomic type "
                                    + fieldType
                                    + ".");
                }
            }
        }
    }

    @Override
    public <X> TypeInformation<X> getTypeAt(String fieldExpression) {

        Matcher matcher = PATTERN_NESTED_FIELDS.matcher(fieldExpression);
        if (!matcher.matches()) {
            if (fieldExpression.equals(ExpressionKeys.SELECT_ALL_CHAR)
                    || fieldExpression.equals(ExpressionKeys.SELECT_ALL_CHAR_SCALA)) {
                throw new InvalidFieldReferenceException(
                        "Wildcard expressions are not allowed here.");
            } else {
                throw new InvalidFieldReferenceException(
                        "Invalid format of tuple field expression \"" + fieldExpression + "\".");
            }
        }

        String fieldStr = matcher.group(1);
        Matcher fieldMatcher = PATTERN_FIELD.matcher(fieldStr);
        if (!fieldMatcher.matches()) {
            throw new RuntimeException("Invalid matcher pattern");
        }
        String field = fieldMatcher.group(2);
        int fieldPos = Integer.valueOf(field);

        if (fieldPos >= this.getArity()) {
            throw new InvalidFieldReferenceException(
                    "Tuple field expression \""
                            + fieldStr
                            + "\" out of bounds of "
                            + this.toString()

View on GitHub (pinned to 2f3c205e92)

Solutions

1. Use a numeric field expression: 'f0', 'f1', ..., 'f{arity-1}' or plain '0', '1', ...
2. If the type is actually a POJO, use PojoTypeInfo.getTypeAt(String) which accepts field names.
3. If the type is a Row, use RowTypeInfo.getTypeAt(String) which accepts both field names and indices.
4. Double-check the TypeInformation subtype at runtime before calling getTypeAt.

Example fix

// before
tupleType.getTypeAt("myField");
// after
tupleType.getTypeAt("f0");

private static final Pattern TUPLE_FIELD = Pattern.compile("(f?)([0-9]+)(\\.(.+))?");
if (!TUPLE_FIELD.matcher(fieldExpr).matches()) {
    throw new IllegalArgumentException("Invalid tuple field expression: " + fieldExpr);
}
tupleType.getTypeAt(fieldExpr);

static boolean isValidTupleFieldExpression(String expr) {
    return expr != null && expr.matches("(f?)([0-9]+)(\\.(.+))?");
}

When it happens

Trigger: Calling tupleType.getTypeAt("name") on a TupleTypeInfoBase (use PojoTypeInfo for named fields). Calling getTypeAt("field1"). Calling getTypeAt("f0.f1.f2") when a nested field is not a CompositeType.

Common situations: Developer treats a Tuple as a POJO and tries to access fields by name. Confusion between Tuple field selectors (integer indices) and POJO field selectors (string names). Passing a Row field name to a Tuple type. Off-by-one or typo in the field expression string.

Related errors

• Wildcard expressions are not allowed here.
• Usage of class Tuple as a type is not allowed. Use a concret
• Tuple needs to be parameterized by using generics.
• Type information extraction for tuples (except Tuple0) canno
• Automatic type extraction is not possible on candidates with

AI-assisted analysis of apache/flink@2f3c205e92 (2026-08-14). Data as JSON: /api/errors/72a3f9e9bfb5b6ed. Report an issue: GitHub.