[FIX] portal_backend: assert the parent menus group on registry load

portal_backend/models/ir_ui_menu.py

@@ -1,18 +1,22 @@
-from odoo import Command, api, models, tools
+from odoo import Command, models
 
 
 class IrUiMenu(models.Model):
     _inherit = "ir.ui.menu"
 
-    @api.model
-    @tools.ormcache("self.env.uid", "debug", "self.env.lang")
-    def load_menus(self, debug):
-        """Assert all parent menus has internal group."""
-        # NOTE:
-        # It is important to do it here to capture the case when portal_backend is already installed and the user
-        # installs another module with a parent menu without internal group.
+    def _register_hook(self):
+        """Assert all parent menus have internal group.
+
+        NOTE:
+        It is done on registry load to capture the case when portal_backend is already installed and the user
+        installs another module with a parent menu without internal group.
+        It can not be done while loading the menus: that route is readonly, so writing there breaks its cursor
+        with "cannot execute INSERT in a read-only transaction" (the request is retried with a read/write one,
+        but the failed query is already logged as an error).
+        """
+        super()._register_hook()
         parent_menus_wo_group = self.sudo().search([("parent_id", "=", False), ("group_ids", "=", False)])
-        parent_menus_wo_group.with_context(from_config=True).write(
-            {"group_ids": [Command.link(self.env.ref("base.group_user").id)]}
-        )
-        return super().load_menus(debug=debug)
+        if parent_menus_wo_group:
+            parent_menus_wo_group.with_context(from_config=True).write(
+                {"group_ids": [Command.link(self.env.ref("base.group_user").id)]}
+            )