diff --git a/addons/project/models/project.py b/addons/project/models/project.py
index 05eace8edc0..52f7ed9d1d7 100644
--- a/addons/project/models/project.py
+++ b/addons/project/models/project.py
@@ -386,7 +386,7 @@ class Task(models.Model):
     @api.onchange('project_id')
     def _onchange_project(self):
         default_partner_id = self.env.context.get('default_partner_id')
-        default_partner = self.env['res.partner'].browse(default_partner_id) if default_partner_id else None
+        default_partner = self.env['res.partner'].browse(default_partner_id) if default_partner_id else self.env['res.partner']
         if self.project_id:
             self.partner_id = self.project_id.partner_id or default_partner
             self.stage_id = self.stage_find(self.project_id.id, [('fold', '=', False)])