问题的解决方案是明确设置 Content-Type 到 undefined 以便您的浏览器或您正在使用的任何客户端都可以设置它并在那里添加该边界值您。令人失望但却是真实的。

The solution to the problem is to explicitly set Content-Type to undefined so that your browser or whatever client you're using can set it and add that boundary value in there for you. Disappointing but true.