octobercms/october · error · SystemException

Form behavior used in :class does not have a model defined.

Error message

Form behavior used in :class does not have a model defined.

What it means

Error "Form behavior used in :class does not have a model defined." thrown in octobercms/october.

Source

Thrown at modules/backend/widgets/Form.php:379

    /**
     * initFormTabs
     */
    protected function initFormTabs()
    {
        $this->allTabs = (object) $this->allTabs;
        $this->allTabs->outside = new FormTabs(['section' => FormTabs::SECTION_OUTSIDE]);
        $this->allTabs->primary = new FormTabs(['section' => FormTabs::SECTION_PRIMARY]);
        $this->allTabs->secondary = new FormTabs(['section' => FormTabs::SECTION_SECONDARY]);
    }

    /**
     * validateModel validates the supplied form model.
     * @return mixed
     */
    protected function validateModel()
    {
        if (!$this->model) {
            throw new SystemException(Lang::get(
                'backend::lang.form.missing_model',
                ['class'=>get_class($this->controller)]
            ));
        }

        $this->data = isset($this->data)
            ? (object) $this->data
            : $this->model;

        // Non-existent models cannot use translatable features
        if (!$this->model->exists) {
            $this->useTranslatable = false;
        }

        return $this->model;
    }

    /**

View on GitHub (pinned to b608633a7e)

When it happens

Trigger: Thrown at modules/backend/widgets/Form.php:379 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/70b4203738fc6e99. Report an issue: GitHub.