diff --git a/addons_extensions/project_task_timesheet_extended/models/project.py b/addons_extensions/project_task_timesheet_extended/models/project.py
index 7c751df39..865bd99da 100644
--- a/addons_extensions/project_task_timesheet_extended/models/project.py
+++ b/addons_extensions/project_task_timesheet_extended/models/project.py
@@ -1127,7 +1127,7 @@ class ProjectProject(models.Model):
                                members are users who can have an access to
                                the tasks related to this project."""
                                    )
-    user_id = fields.Many2one('res.users', string='Project Manager', default=False, tracking=True, required = True,
+    user_id = fields.Many2one('res.users', string='Project Manager', default=False, tracking=True,
                               domain=lambda self: [('id','in',self.env.ref('project_task_timesheet_extended.role_project_manager').user_ids.ids),('groups_id', 'in', [self.env.ref('project.group_project_manager').id,self.env.ref('project_task_timesheet_extended.group_project_supervisor').id]),('share','=',False)],)
 
     # @api.constrains('user_id')