[NEW] account_move_protect_deleting

account_move_protect_deleting/models/__init__.py

@@ -0,0 +1 @@
+from . import account_move

account_move_protect_deleting/models/account_move.py

@@ -0,0 +1,15 @@
+from odoo import models, api, _
+from odoo.exceptions import UserError
+
+class AccountMove(models.Model):
+    _inherit = 'account.move'
+
+    @api.ondelete(at_uninstall=False)
+    def _check_name(self):
+        """ Prevent deletion of a account move if it has been posted "/"
+        """
+
+        if (self.posted_before) :
+            raise UserError(_(""
+                "You cannot delete this account move because it has been validated."
+            ))