diff --git a/issue12799.diff b/issue12799.diff
new file mode 100644
index 0000000..d3180c7
--- /dev/null
+++ b/issue12799.diff
@@ -0,0 +1,15 @@
+diff --git a/sao/src/model.js b/sao/src/model.js
+index 81e8639d9e..8b55441294 100644
+--- a/sao/src/model.js
++++ b/sao/src/model.js
+@@ -2071,6 +2071,10 @@
+                     rec_name = '';
+                 }
+             }
++            if (value < 0) {
++                value = null;
++                rec_name = '';
++            }
+             Sao.setdefault(
+                 record._values, this.name + '.', {}).rec_name = rec_name;
+             Sao.field.Many2One._super.set_client.call(this, record, value,
diff --git a/series b/series
index 13f0cfa..e5f1899 100644
--- a/series
+++ b/series
@@ -83,3 +83,5 @@ counterpart_party_payment_clearing.diff # [account_payment_clearing] Add the pos
 issue12319.diff # [sale_advance_payment] Only create an advance line if the invoice dont have already one.
 
 update_trees_chart_accounts.diff # [account_account] Update trees of chart of accounts with 2 passes
+
+issue12799.diff # [sao] Convert negative id value as None when set by the client