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    Known Issues

    Old libxml library

    A lot of shared hostings are using archaic version of libxml library that does not support amp-compatible html markup. When you are seeing the following error:

    AMP validation had errors:
The mandatory tag 'noscript enclosure for boilerplate' is missing or incorrect.

    That means that DOMDocument parser can’t place <noscript> tag properly according to AMP requirements.

    There are two ways of solving this issue:

    • Contact your hosting and request a libxml library upgrade (2.8.0 or newer is required)
    • Disable third-party Magento module that uses DOMDocument parser

    Broken AMP pages on Magento 2.1.x

    Magento 2.1.x missing event we use in AMP to transform normal tags to amphtml.

    Pull request with this event was accepted Pull Request 3779 but not added in Magento 2.1.x.

    Open lib/internal/Magento/Framework/View/Element/AbstractBlock.php and apply following changes in toHtml method:

    --- a/lib/internal/Magento/Framework/View/Element/AbstractBlock.php
+++ b/lib/internal/Magento/Framework/View/Element/AbstractBlock.php
@@ -665,6 +665,18 @@ abstract class AbstractBlock extends \Magento\Framework\DataObject implements Bl
         }
         $html = $this->_afterToHtml($html);

+        /** @var \Magento\Framework\DataObject */
+        $transportObject = new \Magento\Framework\DataObject(
+            [
+                'html' => $html,
+            ]
+        );
+        $this->_eventManager->dispatch('view_block_abstract_to_html_after', [
+            'block' => $this,
+            'transport' => $transportObject
+        ]);
+        $html = $transportObject->getHtml();
+
         return $html;
     }

    The attribute ‘template’ is not allowed error on Magento 2.1.x

    In Magento 2.1.x you can see a lot of error messages in system.log:

    Element 'referenceBlock', attribute 'template': The attribute 'template' is not allowed.

    Pull request with fix was accepted Pull Request 9772 but not added in Magento 2.1.x.

    Open lib/internal/Magento/Framework/View/Layout/etc/elements.xsd and allow template for blockReferenceType:

    --- a/lib/internal/Magento/Framework/View/Layout/etc/elements.xsd
+++ b/lib/internal/Magento/Framework/View/Layout/etc/elements.xsd
@@ -314,6 +314,7 @@
             <xs:element ref="uiComponent" minOccurs="0" />
         </xs:choice>
         <xs:attribute type="elementNameType" name="name" use="required"/>
+        <xs:attribute type="xs:string" name="template" use="optional"/>
         <xs:attribute type="xs:boolean" name="display" default="true" use="optional"/>
         <xs:attribute type="xs:boolean" name="remove" use="optional"/>
     </xs:complexType>

    Amasty SeoToolKit wrong pagination urls

    Open Amasty\SeoToolKit\Plugin\Pager and find removeFirstPageParam method:

    private function removeFirstPageParam(&$url)
{
    /* check if url not ?p=10*/
    if (strpos($url, 'p=1&') !== false
        || strlen($url) - stripos($url, 'p=1')  === strlen('p=1')//in the end of line
    ) {
        $url = $this->urlHelper->removeRequestParam($url, 'p');
    }
}

    replace with:

    private function removeFirstPageParam(&$url)
{
    /* check if url not ?p=10*/
    if (strpos($url, 'amp=1') === false &&
        (strpos($url, 'p=1&') !== false
        || strlen($url) - stripos($url, 'p=1')  === strlen('p=1'))//in the end of line
    ) {
        $url = $this->urlHelper->removeRequestParam($url, 'p');
    }
}

    Varnish and force AMP

    By default, Varnish returns same cached content for all user agents (desktop and mobile).

    Because of it, Force AMP on mobile devices feature does not work when using Varnish.

    It can be fixed using devicedetect and configuring Varnish to use it.

    1. Download devicedetect and place it near Varnish configuration file, usually /etc/default/varnish or /etc/varnish/

    2. Modify Varnish configuration to use devicedetect. Here is example based on Magento Varnish configuration file located in app/code/Magento/PageCache/etc/varnish4.vcl :

      --- a/app/code/Magento/PageCache/etc/varnish4.vcl
+++ b/app/code/Magento/PageCache/etc/varnish4.vcl
@@ -1,4 +1,7 @@
 vcl 4.0;
+# devicedetect changes start
+include "devicedetect.vcl";
+# devicedetect changes end

 import std;
 # The minimal Varnish version is 4.0
@@ -22,6 +25,10 @@ acl purge {
 }

 sub vcl_recv {
+    # devicedetect changes start
+    call devicedetect;
+    # devicedetect changes end
+
     if (req.method == "PURGE") {
         if (client.ip !~ purge) {
             return (synth(405, "Method not allowed"));
@@ -107,6 +114,15 @@ sub vcl_recv {
         #unset req.http.Cookie;
     }

+    # devicedetect changes start
+    if (req.url ~ "^/\?amp=1"){
+        return (pass);
+    }
+    if (req.http.X-UA-Device ~ "^mobile" || req.http.X-UA-device ~ "^tablet") {
+        return (pass);
+    }
+    # devicedetect changes end
+
     return (hash);
 }

@@ -133,6 +149,18 @@ sub vcl_backend_response {

     set beresp.grace = 3d;

+    # devicedetect changes start
+    if (bereq.http.X-UA-Device) {
+        if (!beresp.http.Vary) { # no Vary at all
+            set beresp.http.Vary = "X-UA-Device";
+        } elsif (beresp.http.Vary !~ "X-UA-Device") { # add to existing Vary
+            set beresp.http.Vary = beresp.http.Vary + ", X-UA-Device";
+        }
+    }
+    # comment this out if you don't want the client to know your classification
+    set beresp.http.X-UA-Device = bereq.http.X-UA-Device;
+    # devicedetect changes end
+
     if (beresp.http.content-type ~ "text") {
         set beresp.do_esi = true;
     }
@@ -176,6 +204,12 @@ sub vcl_backend_response {
 }

 sub vcl_deliver {
+    # devicedetect changes start
+    if ((req.http.X-UA-Device) && (resp.http.Vary)) {
+        set resp.http.Vary = regsub(resp.http.Vary, "X-UA-Device", "User-Agent");
+    }
+    # devicedetect changes end
+
     if (resp.http.X-Magento-Debug) {
         if (resp.http.x-varnish ~ " ") {
             set resp.http.X-Magento-Cache-Debug = "HIT";
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