diff --git a/addons/im_livechat/static/src/models/discuss_sidebar_category_item/discuss_sidebar_category_item.js b/addons/im_livechat/static/src/models/discuss_sidebar_category_item/discuss_sidebar_category_item.js
index 660af89a29f..4d882e929c8 100644
--- a/addons/im_livechat/static/src/models/discuss_sidebar_category_item/discuss_sidebar_category_item.js
+++ b/addons/im_livechat/static/src/models/discuss_sidebar_category_item/discuss_sidebar_category_item.js
@@ -13,7 +13,6 @@ patchRecordMethods('DiscussSidebarCategoryItem', {
             if (this.channel.correspondent && this.channel.correspondent.id > 0) {
                 return this.channel.correspondent.avatarUrl;
             }
-            return '/mail/static/src/img/smiley/avatar.jpg';
         }
         return this._super();
     },
diff --git a/addons/mail/i18n/mail.pot b/addons/mail/i18n/mail.pot
index 1474d532204..3145a900792 100644
--- a/addons/mail/i18n/mail.pot
+++ b/addons/mail/i18n/mail.pot
@@ -404,6 +404,11 @@ msgstr ""
 msgid "<strong>Recommended Activities</strong>"
 msgstr ""
 
+#. module: mail
+#: code:addons/mail/models/mail_channel.py:0
+msgid "A channel of type 'chat' cannot have more than two users."
+msgstr ""
+
 #. module: mail
 #: model:ir.model.fields,help:mail.field_mail_alias__alias_defaults
 #: model:ir.model.fields,help:mail.field_mail_channel__alias_defaults
diff --git a/addons/mail/models/mail_channel.py b/addons/mail/models/mail_channel.py
index 7706f88d367..41fdd0f1535 100644
--- a/addons/mail/models/mail_channel.py
+++ b/addons/mail/models/mail_channel.py
@@ -95,6 +95,14 @@ class Channel(models.Model):
         ('uuid_unique', 'UNIQUE(uuid)', 'The channel UUID must be unique'),
     ]
 
+    # CHAT CONSTRAINT
+
+    @api.constrains('channel_last_seen_partner_ids', 'channel_partner_ids')
+    def _constraint_partners_chat(self):
+        for ch in self.filtered(lambda ch: ch.channel_type == 'chat'):
+            if len(ch.channel_last_seen_partner_ids) > 2 or len(ch.channel_partner_ids) > 2:
+                raise ValidationError(_("A channel of type 'chat' cannot have more than two users."))
+
     # COMPUTE / INVERSE
 
     @api.depends('channel_type')
diff --git a/addons/mail/static/src/models/discuss_sidebar_category_item/discuss_sidebar_category_item.js b/addons/mail/static/src/models/discuss_sidebar_category_item/discuss_sidebar_category_item.js
index e2161739c96..f064f98be0f 100644
--- a/addons/mail/static/src/models/discuss_sidebar_category_item/discuss_sidebar_category_item.js
+++ b/addons/mail/static/src/models/discuss_sidebar_category_item/discuss_sidebar_category_item.js
@@ -2,7 +2,7 @@
 
 import { registerModel } from '@mail/model/model_core';
 import { attr, many2one, one2one } from '@mail/model/model_field';
-import { clear, link } from '@mail/model/model_field_command';
+import { clear } from '@mail/model/model_field_command';
 
 import Dialog from 'web.Dialog';
 
@@ -28,8 +28,11 @@ registerModel({
                 case 'group':
                     return `/web/image/mail.channel/${this.channel.id}/avatar_128?unique=${this.channel.avatarCacheKey}`;
                 case 'chat':
-                    return this.channel.correspondent.avatarUrl;
+                    if (this.channel.correspondent) {
+                        return this.channel.correspondent.avatarUrl;
+                    }
             }
+            return '/mail/static/src/img/smiley/avatar.jpg';
         },
         /**
          * @private
diff --git a/addons/mail/tests/test_mail_channel.py b/addons/mail/tests/test_mail_channel.py
index 794d2bd5689..d45fd66ea90 100644
--- a/addons/mail/tests/test_mail_channel.py
+++ b/addons/mail/tests/test_mail_channel.py
@@ -378,7 +378,7 @@ class TestChannelInternals(MailCommon):
         self.test_channel.with_context(self._test_context).write({
             'channel_partner_ids': [Command.link(self.user_employee.partner_id.id), Command.link(test_partner.id)],
         })
-        test_chat = self.env['mail.channel'].with_context(self._test_context).create({
+        test_chat = self.env['mail.channel'].with_user(self.user_employee).with_context(self._test_context).create({
             'name': 'test',
             'channel_type': 'chat',
             'public': 'private',
diff --git a/addons/mail/views/mail_channel_views.xml b/addons/mail/views/mail_channel_views.xml
index 9387cb7a744..9797c440da2 100644
--- a/addons/mail/views/mail_channel_views.xml
+++ b/addons/mail/views/mail_channel_views.xml
@@ -80,7 +80,8 @@
                                 </group>
                             </page>
                             <page string="Members" name="members">
-                                <field name="channel_last_seen_partner_ids" mode="tree" context="{'active_test': False}">
+                                <field name="channel_type" invisible="1"/>
+                                <field name="channel_last_seen_partner_ids" mode="tree" context="{'active_test': False}" attrs="{'readonly': [('channel_type', '=', 'chat')]}">
                                     <tree string="Members" editable="bottom">
                                         <field name="partner_id" required="1" attrs="{'readonly': [('id', '!=', False)]}"/>
                                         <field name="partner_email" readonly="1"/>