File page-cache.js not loaded in head

Question

I have some problems with form_key when default FULL PAGE CACHE enabled. And i found out that page-cache.js doesn't load in head section. And there is no "X-Cache:" headers. I've tried everything..

Why can it be? And how it should loading?

---

Solved! Solution is here - https://magento.stackexchange.com/a/291924/83140

Answer 1

Answering your question: the most common cause why FPC is not working is persistence of some block which is not cacheable (in layout block has cacheable="false").

You are expecting the wrong indicator. Let's have a look at how FPC works:

<type name="Magento\Framework\App\FrontControllerInterface">
    <plugin name="front-controller-builtin-cache" type="Magento\PageCache\Model\App\FrontController\BuiltinPlugin"/>
    <plugin name="front-controller-varnish-cache" type="Magento\PageCache\Model\App\FrontController\VarnishPlugin"/>
</type>

Here are two ways: if we use native FPC or Varnish. No FrontController native workflow if the page is cached.

Native FPC

public function aroundDispatch(FrontControllerInterface $subject, \Closure $proceed, RequestInterface $request)
{
    $this->version->process();
    if (!$this->config->isEnabled() || $this->config->getType() != \Magento\PageCache\Model\Config::BUILT_IN) {
        return $proceed($request);
    }
    $result = $this->kernel->load();
    if ($result === false) {
        $result = $proceed($request);
        if ($result instanceof ResponseHttp) {
            $this->addDebugHeaders($result);
            $this->kernel->process($result);
        }
    } else {
        $this->addDebugHeader($result, 'X-Magento-Cache-Debug', 'HIT', true);
    }
    return $result;
}

Let's have a look at process()

/**
 * Handle private content version cookie set cookie if it is not set.
 * Increment version on post requests. In all other cases do nothing.
 *
 * @return void
 */
public function process()
{
    if ($this->request->isPost()) {
        $publicCookieMetadata = $this->cookieMetadataFactory->createPublicCookieMetadata()
            ->setDuration(self::COOKIE_PERIOD)
            ->setPath('/')
            ->setSecure($this->request->isSecure())
            ->setHttpOnly(false);
        $this->cookieManager->setPublicCookie(self::COOKIE_NAME, $this->generateValue(), $publicCookieMetadata);
    }
}

Original comment tells everything. When post request we set a cookie with the name private_content_version

Try to load content from cache and if it exists - loads it and set a header with the name X-Magento-Cache-Debug (In developer mode only)

Varnish instead of FPC

public function afterDispatch(FrontControllerInterface $subject, $result)
{
    if ($this->config->getType() == Config::VARNISH && $this->config->isEnabled()
        && $result instanceof ResponseHttp
    ) {
        $this->version->process();

        if ($this->state->getMode() == AppState::MODE_DEVELOPER) {
            $result->setHeader('X-Magento-Debug', 1);
        }
    }

    return $result;
}

Same process() method and header 'X-Magento-Debug'.

Answer 2

Solved. The problem was in custom Magento_Theme default.xml layout. There was

  <referenceContainer name="main">
        <container name="content.top" label="Main Content Top"/>
        <container name="content" label="Main Content Area"/>
        <container name="content.aside" label="Main Content Aside"/>
        <container name="content.bottom" label="Main Content Bottom"/>
    </referenceContainer>

It's the same as in Magento module-theme default.xml . As i can understand - it was wrong redeclaring of containers. Correct me if I'm wrong.