apache/iceberg · error · ValidationException

Cannot validate against a view

Error message

Cannot validate %s against a view

What it means

The interface default validate(ViewMetadata) throws ValidationException when a requirement that only supports tables is validated against view metadata. Each concrete UpdateRequirement implements validate for the metadata type it applies to; passing the wrong type reaches this default and reports the requirement's class name.

Solutions

1. Route table-scoped requirements to validate(TableMetadata) only.
2. Check the requirement class before choosing which metadata object to validate against.
3. Implement the missing validate(ViewMetadata) override if this is a new requirement type.

Example fix

// before
requirement.validate(viewMetadata); // table-only requirement

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

boolean isTableScoped = !(requirement instanceof UpdateRequirement.ViewRequirement);

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

try { requirement.validate(viewMetadata); } catch (ValidationException e) { /* table-only requirement applied to a view; re-dispatch */ }

When it happens

Trigger: Calling UpdateRequirement.validate(ViewMetadata) on a table-scoped requirement such as AssertTableUUID or AssertRefSnapshotID.

Common situations: Shared commit client code applying table requirements during view commits, or vice versa, after refactoring to support views.

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 table
• 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/28436d51d1774ff6. Report an issue: GitHub.

Appendix: source

Thrown at core/src/main/java/org/apache/iceberg/UpdateRequirement.java:34

 * 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");
      }
    }
  }

  class AssertTableUUID implements UpdateRequirement {
    private final String uuid;

    public AssertTableUUID(String uuid) {

View on GitHub (pinned to 86d9c8fc54)