apache/iceberg · error · ValidationException

Cannot validate against a table

Error message

Cannot validate %s against a table

What it means

UpdateRequirement is the interface for commit requirements (assertions on base metadata). Its default validate(TableMetadata) throws ValidationException because each concrete requirement either validates against a table or a view, not both. Calling validate(base) with a TableMetadata on a requirement that only supports views (or calling the interface default directly on an unsupported subtype) hits this throw.

Solutions

1. Dispatch view-scoped requirements to validate(ViewMetadata) instead of validate(TableMetadata).
2. Use the requirement's concrete type (e.g., AssertViewUUID) to decide which metadata type to pass.
3. Upgrade Iceberg if a requirement subclass is missing its table-side validate override.

Example fix

// before
requirement.validate(tableMetadata); // view-only requirement

// after
if (requirement instanceof UpdateRequirement.ViewRequirement) {
  requirement.validate(viewMetadata);
} else {
  requirement.validate(tableMetadata);
}

boolean isViewScoped = requirement instanceof UpdateRequirement.ViewRequirement;

if (requirement instanceof UpdateRequirement.ViewRequirement vr) { vr.validate(viewMetadata); } else { requirement.validate(tableMetadata); }

try { requirement.validate(base); } catch (ValidationException e) { /* wrong metadata type for this requirement; re-dispatch */ }

When it happens

Trigger: Invoking UpdateRequirement.validate(TableMetadata) on a requirement subclass that only overrides validate(ViewMetadata), or on a stub/default implementation.

Common situations: Generic commit-apply code that dispatches all requirements against table metadata without checking whether the requirement is view-scoped.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

• Cannot validate against a view
• Cannot convert date
• Cannot convert dict encoded field
• Cannot convert time
• Cannot convert timestamp

AI-assisted analysis of apache/iceberg@86d9c8fc54 (2026-09-12). Data as JSON: /api/errors/0c288526751b5548. Report an issue: GitHub.

Appendix: source

Thrown at core/src/main/java/org/apache/iceberg/UpdateRequirement.java:29

 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.iceberg;

import org.apache.iceberg.exceptions.CommitFailedException;
import org.apache.iceberg.exceptions.ValidationException;
import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
import org.apache.iceberg.view.ViewMetadata;

/** Represents a requirement for a {@link MetadataUpdate} */
public interface UpdateRequirement {
  default void validate(TableMetadata base) {
    throw new ValidationException(
        "Cannot validate %s against a table", this.getClass().getSimpleName());
  }

  default void validate(ViewMetadata base) {
    throw new ValidationException(
        "Cannot validate %s against a view", this.getClass().getSimpleName());
  }

  class AssertTableDoesNotExist implements UpdateRequirement {
    public AssertTableDoesNotExist() {}

    @Override
    public void validate(TableMetadata base) {
      if (base != null) {
        throw new CommitFailedException("Requirement failed: table already exists");
      }
    }
  }

View on GitHub (pinned to 86d9c8fc54)