我为IIS托管的WebAPI创建了一个DelegatingHandler，如果响应代码为405，它将创建一个自定义响应。
执行此代码时，没有注册其他处理程序。我通过调试和日志记录验证了这一点。
然而，我最终得到的响应是通用的html代码。就好像我的响应被IIS以某种方式覆盖了一样。
有人能告诉我是什么处理程序产生了这个响应吗：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>IIS 10.0 Detailed Error - 405.0 - Method Not Allowed</title>
<style type="text/css">
<!--
body{margin:0;font-size:.7em;font-family:Verdana,Arial,Helvetica,sans-serif;}
code{margin:0;color:#006600;font-size:1.1em;font-weight:bold;}
.config_source code{font-size:.8em;color:#000000;}
pre{margin:0;font-size:1.4em;word-wrap:break-word;}
ul,ol{margin:10px 0 10px 5px;}
ul.first,ol.first{margin-top:5px;}
fieldset{padding:0 15px 10px 15px;word-break:break-all;}
.summary-container fieldset{padding-bottom:5px;margin-top:4px;}
legend.no-expand-all{padding:2px 15px 4px 10px;margin:0 0 0 -12px;}
legend{color:#333333;;margin:4px 0 8px -12px;_margin-top:0px;
font-weight:bold;font-size:1em;}
a:link,a:visited{color:#007EFF;font-weight:bold;}
a:hover{text-decoration:none;}
h1{font-size:2.4em;margin:0;color:#FFF;}
h2{font-size:1.7em;margin:0;color:#CC0000;}
h3{font-size:1.4em;margin:10px 0 0 0;color:#CC0000;}
h4{font-size:1.2em;margin:10px 0 5px 0;
}#header{width:96%;margin:0 0 0 0;padding:6px 2% 6px 2%;font-family:"trebuchet MS",Verdana,sans-serif;
color:#FFF;background-color:#5C87B2;
}#content{margin:0 0 0 2%;position:relative;}
.summary-container,.content-container{background:#FFF;width:96%;margin-top:8px;padding:10px;position:relative;}
.content-container p{margin:0 0 10px 0;
}#details-left{width:35%;float:left;margin-right:2%;
}#details-right{width:63%;float:left;overflow:hidden;
}#server_version{width:96%;_height:1px;min-height:1px;margin:0 0 5px 0;padding:11px 2% 8px 2%;color:#FFFFFF;
background-color:#5A7FA5;border-bottom:1px solid #C1CFDD;border-top:1px solid #4A6C8E;font-weight:normal;
font-size:1em;color:#FFF;text-align:right;
}#server_version p{margin:5px 0;}
table{margin:4px 0 4px 0;width:100%;border:none;}
td,th{vertical-align:top;padding:3px 0;text-align:left;font-weight:normal;border:none;}
th{width:30%;text-align:right;padding-right:2%;font-weight:bold;}
thead th{background-color:#ebebeb;width:25%;
}#details-right th{width:20%;}
table tr.alt td,table tr.alt th{}
.highlight-code{color:#CC0000;font-weight:bold;font-style:italic;}
.clear{clear:both;}
.preferred{padding:0 5px 2px 5px;font-weight:normal;background:#006633;color:#FFF;font-size:.8em;}
-->
</style>
</head>
<body>
<div id="content">
<div class="content-container">
<h3>HTTP Error 405.0 - Method Not Allowed</h3>
<h4>The page you are looking for cannot be displayed because an invalid method (HTTP verb) is being used.</h4>
</div>
<div class="content-container">
<fieldset><h4>Most likely causes:</h4>
<ul> <li>The request sent to the Web server used an HTTP verb that is not allowed by the module configured to handle the request.</li> <li>A request was sent to the server that contained an invalid HTTP verb.</li> <li>The request is for static content and contains an HTTP verb other than GET or HEAD.</li> <li>A request was sent to a virtual directory using the HTTP verb POST and the default document is a static file that does not support HTTP verbs other than GET or HEAD.</li> </ul>
</fieldset>
</div>
<div class="content-container">
<fieldset><h4>Things you can try:</h4>
<ul> <li>Verify the list of verbs enabled for the module handler this request was sent to, and ensure that this verb should be allowed for the Web site.</li> <li>Check the IIS log file to see which verb is not allowed for the request.</li> <li>Create a tracing rule to track failed requests for this HTTP status code. For more information about creating a tracing rule for failed requests, click <a href="http://go.microsoft.com/fwlink/?LinkID=66439">here</a>. </li> </ul>
</fieldset>
</div>
<div class="content-container">
<fieldset><h4>Detailed Error Information:</h4>
<div id="details-left">
<table border="0" cellpadding="0" cellspacing="0">
<tr class="alt"><th>Module</th><td> ManagedPipelineHandler</td></tr>
<tr><th>Notification</th><td> ExecuteRequestHandler</td></tr>
<tr class="alt"><th>Handler</th><td> System.Web.Http.WebHost.HttpControllerHandler</td></tr>
<tr><th>Error Code</th><td> 0x00000000</td></tr>
</table>
</div>
<div id="details-right">
<table border="0" cellpadding="0" cellspacing="0">
<tr class="alt"><th>Requested URL</th><td> http://127.0.0.1:8002/deradapter/tm</td></tr>
<tr><th>Physical Path</th><td> c:inetpubVHOSTTDMSWebIEEE20305SiteDerAdaptertm</td></tr>
<tr class="alt"><th>Logon Method</th><td> Anonymous</td></tr>
<tr><th>Logon User</th><td> Anonymous</td></tr>
</table>
<div class="clear"></div>
</div>
</fieldset>
</div>
<div class="content-container">
<fieldset><h4>More Information:</h4>
This error means that the request sent to the Web server contained an HTTP verb that is not allowed by the configured module handler for the request.
<p><a href="https://go.microsoft.com/fwlink/?LinkID=62293&IIS70Error=405,0,0x00000000,17763">View more information »</a></p>
</fieldset>
</div>
</div>
</body>
</html>
处理程序的代码非常简单：
protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
var result = await base.SendAsync(request, cancellationToken);
if (result.StatusCode != HttpStatusCode.MethodNotAllowed)
{
return result;
}
result.Content = GetResultContent(); //This is the method that simply creates a customized message
result.Content.Headers.ContentType = new MediaTypeHeaderValue("application/sep+xml");
return result;
}
处理程序注册如下：
config.MessageHandlers.Add(new MethodNotAllowedHandler());
没有其他处理程序。
解决我的问题的是将其添加到web.config中：
<system.webServer>
<httpErrors existingResponse="Passthrough" />
</system.webServer>
我在这个链接上找到了这个。
我是从Richard Deeming的评论中找到线索的，所以谢谢你。
基本上，我需要IIS来不处理从WebAPI接收到的错误，而这个配置设置告诉它这一点。