Back-Forward Cache (bfcache)

When a user clicks the browser's back or forward buttons, the back-forward cache (bfcache) restores a complete in-memory snapshot of the page instead of reloading it. This gives near-instant navigation and improves Core Web Vitals scores. Google's Chrome data shows bfcache restores are on average 10x faster than a normal navigation.

Why it is not enabled by default

1. The Cache-Control: no-store header

Magento sets Cache-Control: no-store on all frontend responses. Browsers treat no-store as an explicit opt-out from bfcache regardless of any other headers. This header is set in two places: in PHP via Framework\App\Response\Http::setNoCacheHeaders(), and in the Varnish VCL for stores that use Varnish as a full page cache backend.

2. Stale JavaScript state on restore

When bfcache restores a page, JavaScript state is preserved exactly as it was when the user navigated away. Several Magento core JS components leave UI elements in a broken state after restore, such as disabled buttons, open drawers, or outdated cart counts. Without pageshow handlers to reset this state, the restored page can be in an inconsistent state.

Hyvä's theme module already handles the second blocker for all native Hyvä components. The remaining issue for Hyvä stores is the no-store header.

Enabling bfcache

There are two ways to remove the no-store blocker. Pick one, there is no need to combine them.

Option 1: apply the Magento core patch (recommended)

magento/magento2#40750 is an open pull request that fixes both the PHP header and all Varnish VCL versions at the core level.

Until the PR is merged, use the magento-patch-bfcache repository, which provides ready-made patch files. Clone it into a patches directory in your Magento root and apply using a Composer patch tool such as cweagans/composer-patches or vaimo/composer-patches:

git clone https://github.com/GrimLink/magento-patch-bfcache patches
mv patches/patches.json .
composer patches-relock
composer patches-repatch

With the patch applied, the Hyvä Enable Bfcache setting is not needed.

Option 2: enable the Hyvä setting and update the Varnish VCL

Step 1: Enable the setting

Enable bfcache in the Magento admin under Stores → Configuration → Hyvä Themes → System → Cache Options → Enable Bfcache.

This removes no-store from the Cache-Control header at the PHP level. For stores not using Varnish as the full page cache backend, this is the only step required.

Step 2: Update the Varnish VCL

If you are using Varnish, the no-store directive is also set in the VCL and must be removed separately. The recommended option is the Elgentos VarnishExtended module, which generates an updated VCL that removes no-store along with other improvements.

diff --git a/etc/varnish4.vcl b/etc/varnish4.vcl
index ffb489c..07e0fd6 100644
--- a/etc/varnish4.vcl
+++ b/etc/varnish4.vcl
@@ -212,7 +212,7 @@ sub vcl_deliver {
    if (resp.http.Cache-Control !~ "private" && req.url !~ "^/(pub/)?(media|static)/") {
        set resp.http.Pragma = "no-cache";
        set resp.http.Expires = "-1";
-        set resp.http.Cache-Control = "no-store, no-cache, must-revalidate, max-age=0";
+        set resp.http.Cache-Control = "no-cache, must-revalidate, max-age=0";
    }   
    if (!resp.http.X-Magento-Debug) {
diff --git a/etc/varnish5.vcl b/etc/varnish5.vcl
index 3347b93..6f72ad0 100644
--- a/etc/varnish5.vcl
+++ b/etc/varnish5.vcl
@@ -209,7 +209,7 @@ sub vcl_deliver {
    if (resp.http.Cache-Control !~ "private" && req.url !~ "^/(pub/)?(media|static)/") {
        set resp.http.Pragma = "no-cache";
        set resp.http.Expires = "-1";
-        set resp.http.Cache-Control = "no-store, no-cache, must-revalidate, max-age=0";
+        set resp.http.Cache-Control = "no-cache, must-revalidate, max-age=0";
    }   
    if (!resp.http.X-Magento-Debug) {
diff --git a/etc/varnish6.vcl b/etc/varnish6.vcl
index 4e07ac5..e32be55 100644
--- a/etc/varnish6.vcl
+++ b/etc/varnish6.vcl
@@ -215,7 +215,7 @@ sub vcl_deliver {
    if (resp.http.Cache-Control !~ "private" && req.url !~ "^/(pub/)?(media|static)/") {
        set resp.http.Pragma = "no-cache";
        set resp.http.Expires = "-1";
-        set resp.http.Cache-Control = "no-store, no-cache, must-revalidate, max-age=0";
+        set resp.http.Cache-Control = "no-cache, must-revalidate, max-age=0";
    }   
    if (!resp.http.X-Magento-Debug) {

For Fastly-specific instructions, see the Mage-OS Theme Optimization module documentation.

Using the Mage-OS Theme Optimization module

The Mage-OS Theme Optimization module also ships bfcache support, and it is enabled by default. Besides removing the no-store header, it adds its own pageshow handler script to every page.

How to resolve this depends on which part of the module you rely on:

• You use option 1 or option 2 above: disable the Mage-OS bfcache feature under Stores → Configuration → Advanced → System → Back/Forward Cache → Enable Back/Forward Cache, or run:

  bin/magento config:set system/bfcache/general/enable 0
  

• You use the Mage-OS module to remove the no-store header (for example on Fastly): keep the setting enabled and only remove the handler script. Add the following to the Magento_Theme/layout/default.xml file in your theme:

  <?xml version="1.0"?>
  <page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
      <body>
          <referenceBlock name="theme-optimization.bfcache.main" remove="true"/>
      </body>
  </page>
  

Handling restored page state

When bfcache restores a page, JavaScript state is preserved from the moment the user navigated away. Use the pageshow event with event.persisted to detect a restore and reset any state that needs it.

window.addEventListener('pageshow', (event) => {
    if (event.persisted) {
        // page was restored from bfcache
    }
});

eventListeners: {
    ['@pageshow.window'](event) {
        if (event.persisted) {
            this.closeMenu();
        }
    }
}

Resources

• web.dev: Back/forward cache
• MDN Glossary: bfcache
• Core Fix: magento/magento2#40750
• Patch: magento-patch-bfcache
• Example Gist: for pageshow event