diff --git a/addons/point_of_sale/models/pos_category.py b/addons/point_of_sale/models/pos_category.py
index 1d986867919..6ae690f6b94 100644
--- a/addons/point_of_sale/models/pos_category.py
+++ b/addons/point_of_sale/models/pos_category.py
@@ -1,7 +1,7 @@
 # -*- coding: utf-8 -*-
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 from odoo import api, fields, models, _
-from odoo.exceptions import ValidationError
+from odoo.exceptions import ValidationError, UserError
 
 
 class PosCategory(models.Model):
@@ -28,3 +28,9 @@ class PosCategory(models.Model):
                 cat = cat.parent_id
             return res
         return [(cat.id, " / ".join(reversed(get_names(cat)))) for cat in self]
+
+    def unlink(self):
+        if self.search_count([('id', 'in', self.ids)]):
+            if self.env['pos.session'].sudo().search_count([('state', '!=', 'closed')]):
+                raise UserError(_('You cannot delete a point of sale category while a session is still opened.'))
+        return super(PosCategory, self).unlink()
diff --git a/addons/point_of_sale/models/pos_config.py b/addons/point_of_sale/models/pos_config.py
index f953e3a580f..bc23bb76163 100644
--- a/addons/point_of_sale/models/pos_config.py
+++ b/addons/point_of_sale/models/pos_config.py
@@ -217,6 +217,7 @@ class PosConfig(models.Model):
     rounding_method = fields.Many2one('account.cash.rounding', string="Cash rounding")
     cash_rounding = fields.Boolean(string="Cash Rounding")
     only_round_cash_method = fields.Boolean(string="Only apply rounding on cash")
+    has_active_session = fields.Boolean(compute='_compute_current_session')
 
     @api.depends('use_pricelist', 'available_pricelist_ids')
     def _compute_allowed_pricelist_ids(self):
@@ -252,8 +253,10 @@ class PosConfig(models.Model):
         """If there is an open session, store it to current_session_id / current_session_State.
         """
         for pos_config in self:
+            opened_sessions = pos_config.session_ids.filtered(lambda s: not s.state == 'closed')
             session = pos_config.session_ids.filtered(lambda s: not s.state == 'closed' and not s.rescue)
             # sessions ordered by id desc
+            pos_config.has_active_session = opened_sessions and True or False
             pos_config.current_session_id = session and session[0].id or False
             pos_config.current_session_state = session and session[0].state or False
 
@@ -462,7 +465,13 @@ class PosConfig(models.Model):
     def write(self, vals):
         opened_session = self.mapped('session_ids').filtered(lambda s: s.state != 'closed')
         if opened_session:
-            raise UserError(_('Unable to modify this PoS Configuration because there is an open PoS Session based on it.'))
+            str = []
+            for key in self._get_forbidden_change_fields():
+                if key in vals.keys():
+                    str.append(key)
+            if len(str) > 0:
+                raise UserError(
+                    _("Unable to modify this PoS Configuration because you can't modify " + ", ".join(str)) + " while a session is open.")
         result = super(PosConfig, self).write(vals)
 
         self.sudo()._set_fiscal_position()
@@ -470,6 +479,12 @@ class PosConfig(models.Model):
         self.sudo()._check_groups_implied()
         return result
 
+    def _get_forbidden_change_fields(self):
+        forbidden_keys = ['module_pos_hr', 'cash_control', 'module_pos_restaurant', 'available_pricelist_ids',
+                          'limit_categories', 'iface_available_categ_ids', 'use_pricelist', 'module_pos_discount',
+                          'payment_method_ids', 'iface_tipproduc']
+        return forbidden_keys
+
     def unlink(self):
         # Delete the pos.config records first then delete the sequences linked to them
         sequences_to_delete = self.sequence_id | self.sequence_line_id
diff --git a/addons/point_of_sale/views/pos_config_view.xml b/addons/point_of_sale/views/pos_config_view.xml
index 6fba101c259..6f7300cfb14 100644
--- a/addons/point_of_sale/views/pos_config_view.xml
+++ b/addons/point_of_sale/views/pos_config_view.xml
@@ -36,10 +36,14 @@
                     <field name="is_installed_account_accountant" invisible="1"/>
                     <field name="company_has_template" invisible="1"/>
                     <field name="allowed_pricelist_ids" invisible="1"/>
+                    <field name="has_active_session" invisible="1"/>
                     <div class="oe_title" id="title">
                         <label for="name" class="oe_edit_only"/>
                         <h1><field name="name"/></h1>
                     </div>
+                    <div class="o_notification_alert alert alert-warning" attrs="{'invisible':[('has_active_session','=', False)]}" role="alert">
+                      A session is currently opened for this PoS. Some settings can only be changed after the session is closed.
+                    </div>
                     <div class="row mt16 o_settings_container">
                         <div id="company" class="col-12 col-lg-6 o_setting_box" groups="base.group_multi_company">
                             <div class="o_setting_right_pane">
@@ -54,7 +58,7 @@
                     <div class="row mt16 o_settings_container">
                       <div class="col-12 col-lg-6 o_setting_box">
                         <div class="o_setting_left_pane">
-                          <field name="module_pos_restaurant"/>
+                          <field name="module_pos_restaurant" attrs="{'readonly': [('has_active_session','=', True)]}"/>
                         </div>
                         <div class="o_setting_right_pane">
                           <label for="module_pos_restaurant"/>
@@ -64,7 +68,7 @@
                         <div class="col-12 col-lg-6 o_setting_box"
                              title="Employees can scan their badge or enter a PIN to log in to a PoS session. These credentials are configurable in the *HR Settings* tab of the employee form.">
                             <div class="o_setting_left_pane">
-                                <field name="module_pos_hr"/>
+                                <field name="module_pos_hr" attrs="{'readonly': [('has_active_session','=', True)]}"/>
                             </div>
                             <div class="o_setting_right_pane" id="login_with_employees">
                                 <span class="o_form_label">Login with Employees</span>
@@ -93,7 +97,7 @@
                         </div>
                         <div class="col-12 col-lg-6 o_setting_box" >
                             <div class="o_setting_left_pane">
-                                <field name="limit_categories"/>
+                                <field name="limit_categories" attrs="{'readonly': [('has_active_session','=', True)]}"/>
                             </div>
                             <div class="o_setting_right_pane">
                                 <label for="limit_categories"/>
@@ -101,7 +105,7 @@
                                     Available Product Categories
                                 </div>
                                 <div class="content-group mt16" attrs="{'invisible': [('limit_categories', '=', False)]}">
-                                    <field name="iface_available_categ_ids" widget="many2many_tags"/>
+                                    <field name="iface_available_categ_ids" widget="many2many_tags" attrs="{'readonly': [('has_active_session','=', True)]}"/>
                                 </div>
                                 <div class="content-group mt16" attrs="{'invisible': [('limit_categories', '=', False)]}">
                                     <button name="%(product_pos_category_action)d" icon="fa-arrow-right" type="action" string="PoS Product Categories" class="btn-link"/>
@@ -264,7 +268,7 @@
                         </div>
                         <div class="col-12 col-lg-6 o_setting_box" id="pricelist_setting" groups="product.group_product_pricelist">
                             <div class="o_setting_left_pane">
-                                <field name="use_pricelist"/>
+                                <field name="use_pricelist" attrs="{'readonly': [('has_active_session','=', True)]}"/>
                             </div>
                             <div class="o_setting_right_pane">
                                 <label for="use_pricelist" string="Advanced Pricelists"/>
@@ -274,7 +278,7 @@
                                 <div class="content-group mt16" attrs="{'invisible': [('use_pricelist','=',False)], 'required' : [('use_pricelist', '=', True)]}">
                                     <div class="row mt16">
                                         <label string="Available Pricelists" for="available_pricelist_ids" class="col-lg-3 o_light_label"/>
-                                        <field name="available_pricelist_ids" widget="many2many_tags" domain="['|',('company_id', '=', company_id),('company_id', '=', False)]"/>
+                                        <field name="available_pricelist_ids" widget="many2many_tags" domain="['|',('company_id', '=', company_id),('company_id', '=', False)]" attrs="{'readonly': [('has_active_session','=', True)]}"/>
                                     </div>
                                 </div>
                             </div>
@@ -295,7 +299,7 @@
                         </div>
                         <div class="col-xs-12 col-lg-6 o_setting_box" >
                             <div class="o_setting_left_pane">
-                                <field name="module_pos_discount"/>
+                                <field name="module_pos_discount" attrs="{'readonly': [('has_active_session','=', True)]}"/>
                             </div>
                             <div class="o_setting_right_pane">
                                 <label for="module_pos_discount"/>
@@ -335,7 +339,7 @@
                                     Payment methods available
                                 </div>
                                 <div class="content-group mt16">
-                                    <field name="payment_method_ids" colspan="4" nolabel="1" widget="many2many_tags" required="1"/>
+                                    <field name="payment_method_ids" colspan="4" nolabel="1" widget="many2many_tags" required="1" attrs="{'readonly': [('has_active_session','=', True)]}"/>
                                 </div>
                                 <div>
                                     <button name="%(action_payment_methods_tree)d" icon="fa-arrow-right" type="action" string="Payment Methods" class="btn-link"/>
@@ -361,7 +365,7 @@
                         </div>
                         <div class="col-12 col-lg-6 o_setting_box">
                             <div class="o_setting_left_pane">
-                                <field name="cash_control"/>
+                                <field name="cash_control" attrs="{'readonly': [('has_active_session','=', True)]}"/>
                             </div>
                             <div class="o_setting_right_pane">
                                 <label for="cash_control"/>
@@ -395,7 +399,7 @@
                              id="iface_tipproduct"
                              title="This product is used as reference on customer receipts.">
                             <div class="o_setting_left_pane">
-                                <field name="iface_tipproduct"/>
+                                <field name="iface_tipproduct" attrs="{'readonly': [('has_active_session','=', True)]}"/>
                             </div>
                             <div class="o_setting_right_pane">
                                 <label for="iface_tipproduct" string="Tips"/>
diff --git a/addons/pos_restaurant/models/pos_config.py b/addons/pos_restaurant/models/pos_config.py
index 3316be8ae67..b9807b1ec62 100644
--- a/addons/pos_restaurant/models/pos_config.py
+++ b/addons/pos_restaurant/models/pos_config.py
@@ -48,3 +48,9 @@ class PosConfig(models.Model):
         for table in tables:
             result.append({'id': table.id, 'orders': orders_map.get(table.id, 0)})
         return result
+
+    def _get_forbidden_change_fields(self):
+        forbidden_keys = super(PosConfig, self)._get_forbidden_change_fields()
+        forbidden_keys.append('is_table_management')
+        forbidden_keys.append('floor_ids')
+        return forbidden_keys
diff --git a/addons/pos_restaurant/models/pos_restaurant.py b/addons/pos_restaurant/models/pos_restaurant.py
index 24023b35f73..c1b8716bb4f 100644
--- a/addons/pos_restaurant/models/pos_restaurant.py
+++ b/addons/pos_restaurant/models/pos_restaurant.py
@@ -66,6 +66,15 @@ class RestaurantTable(models.Model):
             table_id = self.create(table).id
         return table_id
 
+    def unlink(self):
+        confs = self.mapped('floor_id').mapped('pos_config_id').filtered(lambda c: c.is_table_management == True)
+        opened_session = self.env['pos.session'].search([('config_id', 'in', confs.ids), ('state', '!=', 'closed')])
+        if opened_session:
+            error_msg = _("You cannot remove a table that is used in a PoS session, close the session(s) first.")
+            if confs:
+                raise UserError(error_msg)
+        return super(RestaurantTable, self).unlink()
+
 
 class RestaurantPrinter(models.Model):
 
diff --git a/addons/pos_restaurant/views/pos_config_views.xml b/addons/pos_restaurant/views/pos_config_views.xml
index 77249d6647d..5d6140037ed 100644
--- a/addons/pos_restaurant/views/pos_config_views.xml
+++ b/addons/pos_restaurant/views/pos_config_views.xml
@@ -67,7 +67,7 @@
                      id="is_table_management"
                      attrs="{'invisible': [('module_pos_restaurant', '=', False)]}">
                     <div class="o_setting_left_pane">
-                        <field name="is_table_management"/>
+                        <field name="is_table_management" attrs="{'readonly': [('has_active_session','=', True)]}"/>
                     </div>
                     <div class="o_setting_right_pane">
                         <label for="is_table_management"/>
@@ -78,7 +78,7 @@
                         <div class="content-group" attrs="{'invisible': [('is_table_management','=',False)]}">
                             <div class="mt16">
                                 <label string="Floors" for="floor_ids" class="o_light_label"/>
-                                <field name="floor_ids" widget="many2many_tags"/>
+                                <field name="floor_ids" widget="many2many_tags" attrs="{'readonly': [('has_active_session','=', True)]}"/>
                             </div>
                             <div>
                                 <button name="%(pos_restaurant.action_restaurant_floor_form)d" icon="fa-arrow-right" type="action" string="Floors" class="btn-link"/>