apache/beam · error · IllegalArgumentException

Unable to get field from

Error message

Unable to get field ${name} from ${originalClazz}

What it means

AvroCoder's reflection helper walks the class hierarchy looking for a declared field with the given name. If neither the class nor any superclass declares it, it throws IllegalArgumentException instead of returning null.

Solutions

1. Verify the field name exists on the class with clazz.getDeclaredField(name) before calling field()
2. Regenerate the SpecificRecord from the current schema so the class contains the requested field
3. Correct the field name typo or casing to match the Java class declaration

Example fix

// before
Field f = coder.field("user_nane");
// after
Field f = coder.field("user_name"); // name matches the declared field in the record class

java.lang.reflect.Field f = null;
for (Class<?> c = recordClass; c != null; c = c.getSuperclass()) {
  try { f = c.getDeclaredField(fieldName); break; } catch (NoSuchFieldException ignored) {}
}
if (f == null) throw new IllegalStateException("Field " + fieldName + " missing on " + recordClass);

static boolean hasField(Class<?> c, String name) {
  for (Class<?> k = c; k != null; k = k.getSuperclass()) {
    try { k.getDeclaredField(name); return true; } catch (NoSuchFieldException ignored) {}
  }
  return false;
}

try { Field f = coder.field(name); } catch (IllegalArgumentException e) { /* fallback to schema-based lookup */ }

When it happens

Trigger: Calling AvroCoder.field(name) (directly or via coder internals) with a field name that does not exist on the record class or any of its superclasses.

Common situations: Schema and Java class drift: schema evolved or was hand-written with a field name the POJO lacks, or a typo'd field name, or reading an old Avro file with a schema field the current compiled SpecificRecord no longer has.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• AVRO schema doesn't match row schema. Row schema
• Couldn't set the specified Avro data model
• Error writing row to Avro
• Unable to access MODEL$ field in SpecificRecordBase class
• Unable to generate a getter for class

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/260a1b07cff76856. Report an issue: GitHub.

Appendix: source

Thrown at sdks/java/extensions/avro/src/main/java/org/apache/beam/sdk/extensions/avro/coders/AvroCoder.java:855

    /**
     * Extract a field from a class. We need to look at the declared fields so that we can see
     * private fields. We may need to walk up to the parent to get classes from the parent.
     */
    private static Field getField(Class<?> originalClazz, String name) {
      Class<?> clazz = originalClazz;
      while (clazz != null) {
        for (Field field : clazz.getDeclaredFields()) {
          AvroName avroName = field.getAnnotation(AvroName.class);
          if (avroName != null && name.equals(avroName.value())) {
            return field;
          } else if (avroName == null && name.equals(field.getName())) {
            return field;
          }
        }
        clazz = clazz.getSuperclass();
      }

      throw new IllegalArgumentException("Unable to get field " + name + " from " + originalClazz);
    }
  }

  /**
   * @return {@code true} if the two {@link AvroCoder} instances have the same class, type and
   *     schema.
   */
  @Override
  public boolean equals(@Nullable Object other) {
    if (this == other) {
      return true;
    }
    if (!(other instanceof AvroCoder)) {
      return false;
    }
    AvroCoder<?> that = (AvroCoder<?>) other;
    return Objects.equals(this.typeDescriptor, that.typeDescriptor)
        && Objects.equals(this.datumFactory, that.datumFactory)

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