OpenCart 2.0.0。- SyntaxError:JSON。解析:JSON数据第1行第1列的数据意外结束。

In OpenCart v. 2.0.0 in /admin when I receive an order I should be able to change status of the order to let the customer know what is going on with her purchase. This functionality is in 'History' tab. Unfortunately I can't change or modify any orders. When I change the status and try to save it Openart gives me an error:In OpenCart v. 2.0.0 in /admin when I receive a