diff --git a/addons/project/i18n/project.pot b/addons/project/i18n/project.pot
index a0e11739b1e..eb372efe260 100644
--- a/addons/project/i18n/project.pot
+++ b/addons/project/i18n/project.pot
@@ -3172,6 +3172,20 @@ msgid ""
 "People invited to collaborate on the project will have portal access rights."
 msgstr ""
 
+#. module: project
+#. odoo-python
+#: code:addons/project/models/res_partner.py:0
+#, python-format
+msgid "Partner company cannot be different from its assigned projects' company"
+msgstr ""
+
+#. module: project
+#. odoo-python
+#: code:addons/project/models/res_partner.py:0
+#, python-format
+msgid "Partner company cannot be different from its assigned tasks' company"
+msgstr ""
+
 #. module: project
 #: model:ir.model.fields,help:project.field_project_project__privacy_visibility
 #: model:ir.model.fields,help:project.field_project_task__project_privacy_visibility
diff --git a/addons/project/models/res_partner.py b/addons/project/models/res_partner.py
index 47e52e504f1..5c84963a670 100644
--- a/addons/project/models/res_partner.py
+++ b/addons/project/models/res_partner.py
@@ -1,19 +1,31 @@
 # -*- coding: utf-8 -*-
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
-from odoo import fields, models
+from odoo import api, fields, models, _
+from odoo.exceptions import UserError
 from odoo.tools import email_normalize
 
 
 class ResPartner(models.Model):
     """ Inherits partner and adds Tasks information in the partner form """
     _inherit = 'res.partner'
-    _check_company_auto = True
 
-    project_ids = fields.One2many('project.project', 'partner_id', string='Projects', check_company=True)
-    task_ids = fields.One2many('project.task', 'partner_id', string='Tasks', check_company=True)
+    project_ids = fields.One2many('project.project', 'partner_id', string='Projects')
+    task_ids = fields.One2many('project.task', 'partner_id', string='Tasks')
     task_count = fields.Integer(compute='_compute_task_count', string='# Tasks')
 
+    @api.constrains('company_id', 'project_ids')
+    def _ensure_same_company_than_projects(self):
+        for partner in self:
+            if partner.company_id and partner.project_ids.company_id and partner.project_ids.company_id != partner.company_id:
+                raise UserError(_("Partner company cannot be different from its assigned projects' company"))
+
+    @api.constrains('company_id', 'task_ids')
+    def _ensure_same_company_than_tasks(self):
+        for partner in self:
+            if partner.company_id and partner.task_ids.company_id and partner.task_ids.company_id != partner.company_id:
+                raise UserError(_("Partner company cannot be different from its assigned tasks' company"))
+
     def _compute_task_count(self):
         # retrieve all children partners and prefetch 'parent_id' on them
         all_partners = self.with_context(active_test=False).search_fetch(
diff --git a/addons/project/tests/test_project_base.py b/addons/project/tests/test_project_base.py
index ec4d40e8701..6e8e32a3003 100644
--- a/addons/project/tests/test_project_base.py
+++ b/addons/project/tests/test_project_base.py
@@ -214,13 +214,16 @@ class TestProjectBase(TestProjectCommon):
         with self.assertRaises(UserError):
             # Cannot change the company of a partner if both the project and its partner have a company
             partner.company_id = company_2
-        with self.assertRaises(UserError):
-            # Cannot set the company of a partner to False if both the project and its partner have a company
-            partner.company_id = False
+        partner.company_id = False
         self.project_pigs.company_id = False
         self.assertFalse(self.project_pigs.company_id, "The company of the project should have been set to False.")
-        partner.company_id = False
         self.project_pigs.company_id = company_1
+        self.project_goats.company_id = company_1
+        self.project_goats.partner_id = partner
+        with self.assertRaises(UserError):
+            # Cannot change the company of a partner that part of multiple projects with different companies
+            self.project_goats.partner_id.company_id = company_2
+
 
         # The project has a company, but the partner has none. The partner can only be set to False/project.company but the project can have any new company.
         with self.assertRaises(UserError):
diff --git a/addons/project_mrp/tests/__init__.py b/addons/project_mrp/tests/__init__.py
index 4fa67e8be11..10a4c2bd379 100644
--- a/addons/project_mrp/tests/__init__.py
+++ b/addons/project_mrp/tests/__init__.py
@@ -2,3 +2,4 @@
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
 from . import test_project_profitability
+from . import test_project_stock
diff --git a/addons/project_mrp/tests/test_project_stock.py b/addons/project_mrp/tests/test_project_stock.py
new file mode 100644
index 00000000000..351d0e71ce0
--- /dev/null
+++ b/addons/project_mrp/tests/test_project_stock.py
@@ -0,0 +1,19 @@
+# -*- coding: utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+from odoo.addons.project.tests.test_project_base import TestProjectCommon
+
+
+class TestProjectStock(TestProjectCommon):
+    def test_check_company(self):
+        """
+            tests editing relation fields of a partner from a project
+        """
+        self.project_pigs.partner_id = self.env['res.partner'].create({
+            'name': 'Jeff Delaney',
+        })
+        self.env['stock.warehouse'].create({
+            'name': 'Hi mom!',
+            'partner_id': self.project_pigs.partner_id.id,
+            'code': 'Fireship',
+        })