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

Missing a blueprint source in the controller.

Error message

Missing a blueprint source in the controller.

What it means

Error "Missing a blueprint source in the controller." thrown in octobercms/october.

Source

Thrown at modules/tailor/behaviors/PreviewController.php:127

    /**
     * hasPreviewPage
     */
    public function hasPreviewPage(): bool
    {
        return $this->getPreviewPageName() !== null;
    }

    /**
     * getPreviewPageName
     */
    protected function getPreviewPageName(): ?string
    {
        if ($this->previewPageName !== null) {
            return $this->previewPageName;
        }

        if (!$blueprint = $this->activeSource) {
            throw new SystemException('Missing a blueprint source in the controller.');
        }

        // Find page with component
        $theme = $this->getTheme();
        $cacheKey = self::getPreviewPageCacheKey($theme);
        $lookupKey = "{$this->componentName}.{$blueprint->handle}";
        $result = [];

        // Check cache
        $cached = Cache::memo()->get($cacheKey, false);
        if ($cached !== false && ($cached = @unserialize($cached, ['allowed_classes' => false])) !== false && is_array($cached)) {
            if (array_key_exists($lookupKey, $cached)) {
                return $cached[$lookupKey];
            }
            else {
                $result = $cached;
            }
        }

View on GitHub (pinned to b608633a7e)

When it happens

Trigger: Thrown at modules/tailor/behaviors/PreviewController.php:127 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/1ed8db6110fdea30. Report an issue: GitHub.