status= cancelled也可能发生在JavaScript事件的ajax请求上:

<script>
  $("#call_ajax").on("click", function(event){
     $.ajax({
        ...    
     });
  });
</script>

<button id="call_ajax">call</button> 

事件成功发送请求，但随后被取消(但由服务器处理)。原因是，元素在单击事件时提交表单，无论您是否对同一单击事件发出任何ajax请求。

为了防止请求被取消，JavaScript event.preventDefault();必须被称为:

<script>
  $("#call_ajax").on("click", function(event){
     event.preventDefault();
     $.ajax({
        ...    
     });
  });
</script>

请求可能已经被跟踪保护插件阻止了。

我们曾遇到过类似的问题，Chrome会取消在帧内或iframes内加载内容的请求，但只是间歇性的，这似乎取决于计算机和/或互联网连接的速度。

这些信息已经过时几个月了，但是我从头开始构建了Chromium，在源代码中挖掘了所有可以取消请求的地方，并在所有这些地方设置了断点以进行调试。根据记忆，Chrome会取消请求的地方只有:

The DOM element that caused the request to be made got deleted (i.e. an IMG is being loaded, but before the load happened, you deleted the IMG node) You did something that made loading the data unnecessary. (i.e. you started loading a iframe, then changed the src or overwrite the contents) There are lots of requests going to the same server, and a network problem on earlier requests showed that subsequent requests weren't going to work (DNS lookup error, earlier (same) request resulted e.g. HTTP 400 error code, etc)

在我们的例子中，我们最终追踪到一个试图将HTML附加到另一个帧的帧，这有时发生在目标帧加载之前。一旦您接触到iframe的内容，它就不能再将资源加载到其中(它如何知道将资源放在哪里?)，因此它会取消请求。

当我在样式表中嵌入web字体时，我已经嵌入了所有类型的字体以及woff, woff2, ttf。最近我注意到Chrome取消请求ttf和woff时，woff2是存在的。我现在使用Chrome版本66.0.3359.181，但我不确定Chrome什么时候开始取消额外的字体类型。

对我来说，这是一条错误的道路。我建议调试的第一步是看看你是否可以加载文件独立的ajax等。

我也遇到过同样的问题，在我们的代码深处，我们有这样的伪代码:

创建iframe 加载iframe提交一个表单 2秒后，移除iframe

thus, when the server takes more than 2 seconds to respond the iframe to which the server was writing the response to, was removed, but the response was still to be written , but there was no iframe to write , thus chrome cancelled the request, thus to avoid this I made sure that the iframe is removed only after the response is over, or you can change the target to "_blank". Thus one of the reason is: when the resource(iframe in my case) that you are writing something in, is removed or deleted before you stop writing to it, the request will be cancelled