apache/beam · error · java.lang.IllegalArgumentException

No field at index

Error message

No field at index <fieldIdx>

What it means

RowWithStorage backs a Row with a simple list of values; getValue(fieldIdx) throws IllegalArgumentException when the requested index is beyond the stored list size. The row's storage contains fewer values than the index asked for, i.e. caller and row disagree on the schema's field count.

Solutions

1. Verify row.getSchema().getFieldCount() before indexing; iterate with row.getValues() or FieldAccessors
2. Rebuild the row supplying values for every schema field
3. If reading old data after a schema change, migrate rows or make the read tolerant of missing trailing fields

Example fix

// before
for (int i = 0; i <= schema.getFieldCount(); i++) row.getValue(i);
// after
for (int i = 0; i < schema.getFieldCount(); i++) row.getValue(i);

if (fieldIdx >= row.getSchema().getFieldCount()) throw new IllegalArgumentException("index " + fieldIdx + " out of range");

boolean hasField(Row row, int idx) { return row.getValues().size() > idx; }

try { return row.getValue(idx); } catch (IllegalArgumentException e) { if (e.getMessage().startsWith("No field at index")) return null; throw e; }

When it happens

Trigger: Calling row.getValue(i) where i >= values.size() — e.g. a Row built with Row.withSchema(...).addValues(...) given fewer values than the schema declares, or code iterating past the schema's field count on a truncated row.

Common situations: Schema changed (field added) but old serialized/stored rows have fewer values; addValues called with a short varargs list; off-by-one loops over row fields.

Related errors

• Cannot provide a coder for a Beam Row. Please provide a…
• Not a primitive type for field name
• Null value set on non-nullable field
• Position was out of bounds for ranges .
• Row expected fields ( ). initialized with <values.size>…

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/d3d95cfc4e26fb16. Report an issue: GitHub.

Appendix: source

Thrown at sdks/java/core/src/main/java/org/apache/beam/sdk/values/RowWithStorage.java:39

import org.apache.beam.sdk.schemas.Schema;
import org.checkerframework.checker.nullness.qual.Nullable;

/** Concrete subclass of {@link Row} that explicitly stores all fields of the row. */
public class RowWithStorage extends Row {
  private final List<@Nullable Object> values;

  RowWithStorage(Schema schema, List<@Nullable Object> values) {
    super(schema);
    this.values = values;
  }

  @Override
  @SuppressWarnings("TypeParameterUnusedInFormals")
  public <T extends @Nullable Object> T getValue(int fieldIdx) {
    if (values.size() > fieldIdx) {
      return (T) values.get(fieldIdx);
    } else {
      throw new IllegalArgumentException("No field at index " + fieldIdx);
    }
  }

  @Override
  public List<@Nullable Object> getValues() {
    return values;
  }

  @Override
  public int getFieldCount() {
    return values.size();
  }
}

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