diff --git a/addons/web/static/lib/tempusdominus/tempusdominus.js b/addons/web/static/lib/tempusdominus/tempusdominus.js
index 6a1d9544fec..bcda3437db2 100644
--- a/addons/web/static/lib/tempusdominus/tempusdominus.js
+++ b/addons/web/static/lib/tempusdominus/tempusdominus.js
@@ -45,7 +45,14 @@ var DateTimePicker = function ($, moment) {
         EVENT_KEY = '.' + DATA_KEY,
         DATA_API_KEY = '.data-api',
         Selector = {
-        DATA_TOGGLE: '[data-toggle="' + DATA_KEY + '"]'
+        // /!\ ODOO PATCH: ensure the datetimepickers can be toggled only after
+        // the Odoo lazy loader finished loading all lazy scripts. Another
+        // solution could have been to temporarily removing the data-toggle
+        // attributes during lazyloading but that would not have been stable as
+        // custom code could search for data-toggle elements while the lazy
+        // loading is being performed. Without this, clicking too soon on a
+        // datetimepicker would not use the right format and UI options.
+        DATA_TOGGLE: 'body:not(.o_lazy_js_waiting) [data-toggle="' + DATA_KEY + '"]'
     },
         ClassName = {
         INPUT: NAME + '-input'
diff --git a/addons/web/static/src/legacy/js/public/lazyloader.js b/addons/web/static/src/legacy/js/public/lazyloader.js
index 8ca0948cde8..37b5cab17ad 100644
--- a/addons/web/static/src/legacy/js/public/lazyloader.js
+++ b/addons/web/static/src/legacy/js/public/lazyloader.js
@@ -10,7 +10,7 @@ var blockFunction = function (ev) {
 var waitingLazy = false;
 
 /**
- * Blocks the DOM sections which explicitely require the lazy loaded JS to be
+ * Blocks the DOM sections which explicitly require the lazy loaded JS to be
  * working (those sections should be marked with the 'o_wait_lazy_js' class).
  *
  * @see stopWaitingLazy
@@ -28,6 +28,8 @@ function waitLazy() {
             element.addEventListener(evType, blockFunction);
         });
     }
+
+    document.body.classList.add('o_lazy_js_waiting');
 }
 /**
  * Unblocks the DOM sections blocked by @see waitLazy and removes the related
@@ -47,6 +49,8 @@ function stopWaitingLazy() {
         });
         element.classList.remove('o_wait_lazy_js');
     }
+
+    document.body.classList.remove('o_lazy_js_waiting');
 }
 
 // Start waiting for lazy loading as soon as the DOM is available