apache/iceberg · error · NullPointerException

does not support null keys

Error message

 does not support null keys

What it means

PartitionMap only supports keys that are Pair<Integer, StructLike> (specId + partition data). When a key is null — which no supported key can be — it throws a NullPointerException naming the class, since a null partition key is meaningless.

Solutions

1. Never call get/put with null keys on a PartitionMap
2. Ensure partition data construction never yields null pairs
3. Add a null check before accessing the PartitionMap

Example fix

// before
map.get(null, null);
// after
if (key != null) { map.get(key, null); }

if (key == null) throw new IllegalArgumentException("PartitionMap requires non-null Pair keys");

boolean isPartitionKey(Object k) { return k instanceof Pair && ((Pair<?, ?>) k).first() instanceof Integer; }

try { map.get(key, null); } catch (NullPointerException e) { /* null key path — supply default */ }

When it happens

Trigger: Calling get(key, default) (via the doAction path) with key == null on a PartitionMap, typically from generic Map<StructLike, V> code that passes null keys.

Common situations: Generic map-processing utilities that pass null; data corrupted by upstream null partition values.

Related errors

• Cannot get value
• Cannot parse :
• Cannot set value
• Cannot set value
• Invalid transform argument

AI-assisted analysis of apache/iceberg@86d9c8fc54 (2026-09-12). Data as JSON: /api/errors/f41f37a81f6a1d8a. Report an issue: GitHub.

Appendix: source

Thrown at core/src/main/java/org/apache/iceberg/util/PartitionMap.java:210

    PartitionSpec spec = specs.get(entry.getKey());
    return entry.getValue().entrySet().stream().map(innerEntry -> toString(spec, innerEntry));
  }

  private String toString(PartitionSpec spec, Entry<StructLike, V> entry) {
    StructLike struct = entry.getKey();
    V value = entry.getValue();
    return spec.partitionToPath(struct) + " -> " + (value == this ? "(this Map)" : value);
  }

  private <R> R execute(Object key, BiFunction<Integer, StructLike, R> action, R defaultValue) {
    if (key instanceof Pair) {
      Object first = ((Pair<?, ?>) key).first();
      Object second = ((Pair<?, ?>) key).second();
      if (first instanceof Integer && (second == null || second instanceof StructLike)) {
        return action.apply((Integer) first, (StructLike) second);
      }
    } else if (key == null) {
      throw new NullPointerException(getClass().getName() + " does not support null keys");
    }

    return defaultValue;
  }

  private static class PartitionEntry<V> implements Entry<Pair<Integer, StructLike>, V> {
    private final int specId;
    private final Entry<StructLike, V> structAndValue;

    private PartitionEntry(int specId, Entry<StructLike, V> structAndValue) {
      this.specId = specId;
      this.structAndValue = structAndValue;
    }

    @Override
    public Pair<Integer, StructLike> getKey() {
      return Pair.of(specId, structAndValue.getKey());
    }

View on GitHub (pinned to 86d9c8fc54)