apache/iceberg · warning · CommitFailedException

Cannot commit to table

Error message

Cannot commit to table %s metadata location from %s to %s because it has been concurrently modified to %s

What it means

This is the optimistic-concurrency conflict of the in-memory catalog: the commit expected the table's metadata location to equal oldLocation, but the map holds a different existingLocation, meaning another committer advanced the table in between. Per Iceberg's commit contract, CommitFailedException signals the caller to refresh and retry the update against the new state.

Solutions

1. Retry the commit: catch CommitFailedException, call table.refresh(), re-apply the update, and commit again (Iceberg's RetryUtil/Tasks.foreach with retry works well).
2. Reduce conflict windows by shortening transaction scopes or partitioning work across distinct tables.
3. Ensure every retry reloads/refreshes metadata; never reuse stale TableMetadata.

Example fix

// before
table.updateSchema().addColumn("c", Types.IntegerType.get()).commit();

// after
Tasks.foreach(table)
    .retry(3)
    .onlyOn(CommitFailedException.class)
    .run(t -> t.refresh());
table.refresh();
table.updateSchema().addColumn("c", Types.IntegerType.get()).commit();

try { table.commit(update); } catch (CommitFailedException e) { table.refresh(); /* re-apply update on refreshed metadata and retry, bounded attempts */ }

When it happens

Trigger: Two writers load the same table and both call commit(); the loser sees existingLocation != oldLocation and neither base nor existingLocation is null. Any concurrent metadata operation (schema update, append, partition spec change) on the same table.

Common situations: Multiple executors/threads appending to one table; concurrent schema evolution and writes; retry loops that do not refresh the table before recommitting.

Related errors

• Cannot commit to view
• View was updated concurrently
• Cannot commit: Base metadata location
• Cannot commit changes based on stale table metadata
• Cannot commit file that conflicts with existing partition

AI-assisted analysis of apache/iceberg@86d9c8fc54 (2026-09-12). Data as JSON: /api/errors/bc274ee4daac14bd. Report an issue: GitHub.

Appendix: source

Thrown at core/src/main/java/org/apache/iceberg/inmemory/InMemoryCatalog.java:454

        if (views.containsKey(tableIdentifier)) {
          throw new AlreadyExistsException(
              "View with same name already exists: %s", tableIdentifier);
        }

        tables.compute(
            tableIdentifier,
            (k, existingLocation) -> {
              if (!Objects.equal(existingLocation, oldLocation)) {
                if (null == base) {
                  throw new AlreadyExistsException("Table already exists: %s", tableName());
                }

                if (null == existingLocation) {
                  throw new NoSuchTableException("Table does not exist: %s", tableName());
                }

                throw new CommitFailedException(
                    "Cannot commit to table %s metadata location from %s to %s "
                        + "because it has been concurrently modified to %s",
                    tableIdentifier, oldLocation, newLocation, existingLocation);
              }
              return newLocation;
            });
      }
    }

    @Override
    public FileIO io() {
      return fileIO;
    }

    @Override
    protected String tableName() {
      return fullTableName;
    }

View on GitHub (pinned to 86d9c8fc54)