diff --git a/news/+ajax_load.feature.md b/news/+ajax_load.feature.md
new file mode 100644
index 00000000..36529763
--- /dev/null
+++ b/news/+ajax_load.feature.md
@@ -0,0 +1 @@
+(Re)Introduce the ajax_load theme parameter and skip diazo theming, if set.
diff --git a/plonetheme/barceloneta/configure.zcml b/plonetheme/barceloneta/configure.zcml
index 5e8ccc00..cc47c0e4 100644
--- a/plonetheme/barceloneta/configure.zcml
+++ b/plonetheme/barceloneta/configure.zcml
@@ -7,6 +7,7 @@
 
   <include package="plone.resource" />
   <include package="plone.app.theming" />
+  <include package=".upgrades" />
 
   <!-- Diazo themes -->
   <plone:static
@@ -23,13 +24,4 @@
       directory="profiles/default"
       />
 
-  <!-- upgrade step -->
-  <genericsetup:upgradeDepends
-      title="Upgrade registry"
-      profile="plonetheme.barceloneta:default"
-      source="1"
-      destination="2"
-      import_steps="plone.app.registry"
-      />
-
 </configure>
diff --git a/plonetheme/barceloneta/profiles/default/metadata.xml b/plonetheme/barceloneta/profiles/default/metadata.xml
index c2f6ea9c..42512b87 100644
--- a/plonetheme/barceloneta/profiles/default/metadata.xml
+++ b/plonetheme/barceloneta/profiles/default/metadata.xml
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <metadata>
-  <version>2</version>
+  <version>3</version>
   <dependencies>
     <dependency>profile-plone.app.theming:default</dependency>
   </dependencies>
diff --git a/plonetheme/barceloneta/theme/manifest.cfg b/plonetheme/barceloneta/theme/manifest.cfg
index 174bb468..c2d2e7cb 100644
--- a/plonetheme/barceloneta/theme/manifest.cfg
+++ b/plonetheme/barceloneta/theme/manifest.cfg
@@ -16,4 +16,5 @@ development-js =
 production-js =
 
 [theme:parameters]
+ajax_load = python:request.get('ajax_load')
 portal_url = portal_state/portal_url
diff --git a/plonetheme/barceloneta/theme/rules.xml b/plonetheme/barceloneta/theme/rules.xml
index fd231042..c21ed356 100644
--- a/plonetheme/barceloneta/theme/rules.xml
+++ b/plonetheme/barceloneta/theme/rules.xml
@@ -9,6 +9,7 @@
   <!-- <xi:include href="++theme++barceloneta/grid-col-marker.xml"/> -->
 
   <theme href="index.html" />
+  <notheme if="$ajax_load" /><!-- don't theme ajax requests -->
   <notheme css:if-not-content="#visual-portal-wrapper" />
   <notheme css:if-content=".template-manage-viewlets" />
 
diff --git a/plonetheme/barceloneta/upgrades/__init__.py b/plonetheme/barceloneta/upgrades/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/plonetheme/barceloneta/upgrades/configure.zcml b/plonetheme/barceloneta/upgrades/configure.zcml
new file mode 100644
index 00000000..6e25a70e
--- /dev/null
+++ b/plonetheme/barceloneta/upgrades/configure.zcml
@@ -0,0 +1,22 @@
+<configure
+    xmlns="http://namespaces.zope.org/zope"
+    xmlns:genericsetup="http://namespaces.zope.org/genericsetup"
+    >
+
+  <genericsetup:upgradeDepends
+      title="Upgrade registry"
+      profile="plonetheme.barceloneta:default"
+      source="1"
+      destination="2"
+      import_steps="plone.app.registry"
+      />
+
+  <genericsetup:upgradeStep
+      title="Add ajax_load theme parameter."
+      profile="plonetheme.barceloneta:default"
+      source="2"
+      destination="3"
+      handler=".upgrades.reload_theme"
+      />
+
+</configure>
diff --git a/plonetheme/barceloneta/upgrades/upgrades.py b/plonetheme/barceloneta/upgrades/upgrades.py
new file mode 100644
index 00000000..6869e873
--- /dev/null
+++ b/plonetheme/barceloneta/upgrades/upgrades.py
@@ -0,0 +1,14 @@
+from plone.app.theming import utils as theme_utils
+
+import logging
+
+
+logger = logging.getLogger(__name__)
+
+
+def reload_theme(context):
+    # Reload theme to add ajax_load theme parameter.
+    if theme_utils.getCurrentTheme() == "barceloneta":
+        theme = theme_utils.getTheme("barceloneta")
+        theme_utils.applyTheme(theme)
+        logger.info("Reloaded Barceloneta.")