octobercms/october · error · ApplicationException

To display list as a tree, the model {$modelClass} must impl

Error message

To display list as a tree, the model {$modelClass} must implement methods found in October\Contracts\Database\TreeInterface, or set showTree to false

What it means

Error "To display list as a tree, the model {$modelClass} must implement methods found in October\Contracts\Database\TreeInterface, or set showTree to false" thrown in octobercms/october.

Source

Thrown at modules/backend/widgets/ListStructure.php:327

        }

        foreach ($records as $record) {
            if ($record->getChildCount()) {
                return true;
            }
        }

        return false;
    }

    /**
     * validateTree validates the model and settings if useStructure is used
     */
    public function validateTree()
    {
        if (!$this->model->isClassInstanceOf(\October\Contracts\Database\TreeInterface::class)) {
            $modelClass = get_class($this->model);
            throw new ApplicationException(
                "To display list as a tree, the model {$modelClass} must implement methods found in October\Contracts\Database\TreeInterface, or set showTree to false"
            );
        }
    }

    /**
     * useSortOrdering
     */
    public function useSortOrdering(): bool
    {
        return $this->includeSortOrders || $this->model->isClassInstanceOf(\October\Contracts\Database\SortableInterface::class);
    }

    /**
     * onReorder
     */
    public function onReorder()
    {

View on GitHub (pinned to b608633a7e)

When it happens

Trigger: Thrown at modules/backend/widgets/ListStructure.php:327 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of octobercms/october@b608633a7e (2026-08-21). Data as JSON: /api/errors/202d77e9a661e712. Report an issue: GitHub.