diff --git a/addons/project/models/project.py b/addons/project/models/project.py
index 2355eba348f..6509cac3e25 100644
--- a/addons/project/models/project.py
+++ b/addons/project/models/project.py
@@ -593,7 +593,7 @@ class Task(models.Model):
     subtask_count = fields.Integer("Sub-task count", compute='_compute_subtask_count')
     email_from = fields.Char(string='Email From', help="These people will receive email.", index=True,
         compute='_compute_email_from', store="True", readonly=False)
-    allowed_user_ids = fields.Many2many('res.users', string="Visible to", groups='project.group_project_manager', compute='_compute_allowed_user_ids', store=True, readonly=False)
+    allowed_user_ids = fields.Many2many('res.users', string="Visible to", groups='project.group_project_manager', compute='_compute_allowed_user_ids', store=True, readonly=False, copy=False)
     project_privacy_visibility = fields.Selection(related='project_id.privacy_visibility', string="Project Visibility")
     # Computed field about working time elapsed between record creation and assignation/closing.
     working_hours_open = fields.Float(compute='_compute_elapsed', string='Working hours to assign', store=True, group_operator="avg")