diff --git a/amptheme/amptheme.theme b/amptheme/amptheme.theme
index 2d29b70..0374e8c 100644
--- a/amptheme/amptheme.theme
+++ b/amptheme/amptheme.theme
@@ -205,55 +205,57 @@ function amptheme_preprocess_block(&$variables) {
       if ($variables['content']['site_logo']['#access'] && ($logo_uri = $variables['content']['site_logo']['#uri'])) {
         // Check if logo is an SVG.
         if (substr(strrev($logo_uri), 0, 4) === strrev('.svg')) {
-          // If logo begins with '/', create an absolute URL with domain name.
+          // The logo URI should be a relative path.
           if (substr($logo_uri, 0, 1) === '/') {
-            $logoUrl = \Drupal\Core\Url::fromUserInput($logo_uri);
-            $logoUrl->setAbsolute();
-            $logo_absolute = $logoUrl->toString();
+            $logo_uri = DRUPAL_ROOT . $logo_uri;
           }
-          else {
-            $logo_absolute = $logo_uri;
-          }
-
-          // Load XML for SVG file.
-          $logo_xml = simplexml_load_file($logo_absolute);
-          $logo_attributes = $logo_xml->attributes();
 
-          // SVG needs viewBox property in order to obtain height and width.
-          if (property_exists($logo_attributes, 'viewBox')) {
-            $logo_viewbox = (string) $logo_attributes->viewBox;
-            $logo_viewbox_coordinates = [];
+          if (file_exists($logo_uri)) {
+            // Load XML for SVG file.
+            $logo_xml = simplexml_load_file($logo_uri);
+            $logo_attributes = $logo_xml ? $logo_xml->attributes() : NULL;
+          }
 
-            // Create array of viewBox coordinates depending on item delimiter.
-            if (strpos($logo_viewbox, ',') !== false) {
-              $logo_viewbox_coordinates = explode(',', $logo_viewbox);
-            }
-            elseif (strpos($logo_viewbox, ' ') !== false) {
-              $logo_viewbox_coordinates = explode(' ', $logo_viewbox);
+          if (!empty($logo_attributes)) {
+            // The amp-img tag generated for the logo requires height and width to be defined.
+            if (property_exists($logo_attributes, 'height') && property_exists($logo_attributes, 'width')) {
+              $variables['site_logo_height'] = round($logo_attributes->height, 0);
+              $variables['site_logo_width'] = round($logo_attributes->width, 0);
             }
+            // Use the SVG viewBox property in order to obtain height and width.
+            elseif (property_exists($logo_attributes, 'viewBox')) {
+              $logo_viewbox = (string) $logo_attributes->viewBox;
+              $logo_viewbox_coordinates = [];
 
-            // Get SVG height and width from full viewBox coordinates.
-            if (!empty($logo_viewbox_coordinates[2]) && !empty($logo_viewbox_coordinates[3])) {
-              $variables['site_logo_height'] = round($logo_viewbox_coordinates[3], 0);
-              $variables['site_logo_width'] = round($logo_viewbox_coordinates[2], 0);
+              // Create array of viewBox coordinates depending on item delimiter.
+              if (strpos($logo_viewbox, ',') !== false) {
+                $logo_viewbox_coordinates = explode(',', $logo_viewbox);
+              }
+              elseif (strpos($logo_viewbox, ' ') !== false) {
+                $logo_viewbox_coordinates = explode(' ', $logo_viewbox);
+              }
+
+              // Get SVG height and width from full viewBox coordinates.
+              if (!empty($logo_viewbox_coordinates[2]) && !empty($logo_viewbox_coordinates[3])) {
+                $variables['site_logo_height'] = round($logo_viewbox_coordinates[3], 0);
+                $variables['site_logo_width'] = round($logo_viewbox_coordinates[2], 0);
+              }
             }
           }
         }
         // If logo is not an SVG, we can use the image factory service.
         else {
-          // Force path to be stream wrapped uri.
+          // The logo URI should be a relative path.
           if (substr($logo_uri, 0, 1) === '/') {
-            global $base_root;
-            $logo_uri = $base_root . $logo_uri;
-            $public_stream_base_url = PublicStream::baseUrl();
-            if (substr($logo_uri, 0, strlen($public_stream_base_url)) == $public_stream_base_url) {
-              $logo_uri = file_build_uri(substr($logo_uri, strlen($public_stream_base_url)));
-            }
+            $logo_uri = DRUPAL_ROOT . $logo_uri;
+          }
+
+          if (file_exists($logo_uri)) {
+            /** @var ImageInterface $logo_image */
+            $logo_image = \Drupal::service('image.factory')->get($logo_uri);
           }
 
-          /** @var ImageInterface $logo_image */
-          $logo_image = \Drupal::service('image.factory')->get($logo_uri);
-          if ($logo_image->isValid()) {
+          if (!empty($logo_image) && $logo_image->isValid()) {
             // Get height and width of logo from image factory service.
             $variables['site_logo_height'] = $logo_image->getHeight();
             $variables['site_logo_width'] = $logo_image->getWidth();