octobercms/october · error · October\Rain\Exception\ApplicationException

Cannot preview without the CMS module installed!

Error message

Cannot preview without the CMS module installed!

What it means

Error "Cannot preview without the CMS module installed!" thrown in octobercms/october.

Source

Thrown at modules/tailor/behaviors/PreviewController.php:59

     */
    protected $componentName;

    /**
     * setPreviewPageContext
     */
    public function setPreviewPageContext(string $componentName, Blueprint $activeSource)
    {
        $this->componentName = $componentName;
        $this->activeSource = $activeSource;
    }

    /**
     * onPreview previews the record
     */
    public function onPreview($recordId = null)
    {
        if (!System::hasModule('Cms')) {
            throw new ApplicationException('Cannot preview without the CMS module installed!');
        }

        if (!$pageName = $this->getPreviewPageName()) {
            throw new ApplicationException('There is no page that uses the necessary component');
        }

        // Get model from page action
        $model = $this->controller->formGetModel();

        // Update the record for preview
        $this->performSaveOnModel(
            $model,
            $this->controller->formGetWidget()->getSaveData(),
            $this->controller->formGetWidget()->getSessionKey()
        );

        // A preview page is already open
        if ($existingToken = post('preview_token')) {

View on GitHub (pinned to b608633a7e)

When it happens

Trigger: Thrown at modules/tailor/behaviors/PreviewController.php:59 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/54fa54454ede39cb. Report an issue: GitHub.