diff --git a/addons/mail/static/src/js/thread_field.js b/addons/mail/static/src/js/thread_field.js
index 218a4b552ec..2d809def129 100644
--- a/addons/mail/static/src/js/thread_field.js
+++ b/addons/mail/static/src/js/thread_field.js
@@ -112,7 +112,10 @@ var ThreadField = AbstractField.extend({
      */
     _fetchAndRenderThread: function (options) {
         var self = this;
-        if (!this._documentThread) {
+        if (!this._isMessagingReady) {
+            self._threadWidget.renderLoading();
+            return Promise.resolve();
+        } else if (!this._documentThread) {
             var thread = new CreateModeDocumentThread();
             options = { isCreateMode: true };
             self._threadWidget.render(thread, options);
@@ -199,6 +202,7 @@ var ThreadField = AbstractField.extend({
             return;
         }
         this._setDocumentThread();
+        this._render();
     },
     /**
      * @private
diff --git a/addons/mail/static/src/js/thread_widget.js b/addons/mail/static/src/js/thread_widget.js
index 9550931ad95..3ec66d02520 100644
--- a/addons/mail/static/src/js/thread_widget.js
+++ b/addons/mail/static/src/js/thread_widget.js
@@ -55,6 +55,7 @@ var ThreadWidget = Widget.extend({
      */
     init: function (parent, options) {
         this._super.apply(this, arguments);
+        this.attachments = [];
         // options when the thread is enabled (e.g. can send message,
         // interact on messages, etc.)
         this._enabledOptions = _.defaults(options || {}, {
@@ -220,6 +221,14 @@ var ThreadWidget = Widget.extend({
         }
     },
 
+    /**
+     * Render thread widget when loading, i.e. when messaging is not yet ready.
+     * @see /mail/init_messaging
+     */
+    renderLoading: function () {
+        this.$el.html(QWeb.render('mail.widget.ThreadLoading'));
+    },
+
     //--------------------------------------------------------------------------
     // Public
     //--------------------------------------------------------------------------
diff --git a/addons/mail/static/src/scss/thread.scss b/addons/mail/static/src/scss/thread.scss
index ef220afa06c..c64b3f6aefd 100644
--- a/addons/mail/static/src/scss/thread.scss
+++ b/addons/mail/static/src/scss/thread.scss
@@ -1,3 +1,13 @@
+.o_mail_thread_loading {
+    display: flex;
+    align-items: center;
+    justify-content: center;
+}
+
+.o_mail_thread_loading_icon {
+    margin-right: 5px;
+}
+
 .o_mail_thread, .o_mail_activity {
     .o_thread_show_more {
         text-align: center;
diff --git a/addons/mail/static/src/xml/thread.xml b/addons/mail/static/src/xml/thread.xml
index 24370c65e4e..31614cf4f4f 100644
--- a/addons/mail/static/src/xml/thread.xml
+++ b/addons/mail/static/src/xml/thread.xml
@@ -30,6 +30,12 @@
         </div>
     </t>
 
+    <!-- Rendering of thread when messaging not yet ready -->
+    <div t-name="mail.widget.ThreadLoading" class="o_mail_thread_loading">
+        <i class="o_mail_thread_loading_icon fa fa-spinner fa-spin"/>
+        <span>Please wait...</span>
+    </div>
+
     <!--
         @param {mail.DocumentViewer} widget
     -->
diff --git a/addons/mail/static/tests/chatter_tests.js b/addons/mail/static/tests/chatter_tests.js
index 02242f3ef2a..81742d8d2c2 100644
--- a/addons/mail/static/tests/chatter_tests.js
+++ b/addons/mail/static/tests/chatter_tests.js
@@ -203,6 +203,49 @@ QUnit.module('Chatter', {
     }
 });
 
+QUnit.test('messaging becomes ready', async function (assert) {
+    assert.expect(2);
+
+    const initMessagingProm = testUtils.makeTestPromise();
+    const form = await createView({
+        View: FormView,
+        model: 'partner',
+        data: this.data,
+        services: this.services,
+        arch: `<form string="Partners">
+                <sheet>
+                    <field name="foo"/>
+                </sheet>
+                <div class="oe_chatter">
+                    <field name="message_ids" widget="mail_thread"/>
+                </div>
+            </form>`,
+        async mockRPC(route, args) {
+            const _super = this._super.bind(this, route, args); // limitation on class.js with async/await
+            if (route === '/mail/init_messaging') {
+                await initMessagingProm;
+            }
+            return _super();
+        },
+        res_id: 2,
+    });
+    await testUtils.nextTick();
+    assert.containsOnce(
+        form,
+        '.o_mail_thread_loading',
+        "thread should be loading when messaging is not yet ready");
+
+    // simulate messaging becoming ready
+    initMessagingProm.resolve();
+    await testUtils.nextTick();
+    assert.containsNone(
+        form,
+        '.o_mail_thread_loading',
+        "thread should no longer be loading when messaging becomes ready");
+
+    form.destroy();
+});
+
 QUnit.test('basic rendering', async function (assert) {
     assert.expect(9);