Blazor 呈现组件但立即无法连接答案

【问题标题】：Blazor renders components but immediately fails to connectBlazor 呈现组件但立即无法连接
【发布时间】：2020-11-09 04:59:10
【问题描述】：

我已关注 the documentation（和许多博客），将 blazor 组件添加到剃须刀页面应用程序。剃须刀页面完美呈现组件，但随后立即“尝试重新连接”，这总是失败。控制台输出显示（显然是在本地主机上运行）：

[2020-07-20T00:22:59.957Z] Information: Normalizing '_blazor' to 'https://localhost:44306/_blazor'.
blazor.server.js:1 [2020-07-20T00:22:59.961Z] Debug: Starting HubConnection.
blazor.server.js:1 [2020-07-20T00:22:59.969Z] Debug: Starting connection with transfer format 'Binary'.
blazor.server.js:1 [2020-07-20T00:22:59.970Z] Debug: Sending negotiation request: https://localhost:44306/_blazor/negotiate?negotiateVersion=1.
blazor.server.js:1 [2020-07-20T00:23:00.145Z] Debug: Selecting transport 'WebSockets'.
blazor.server.js:1 [2020-07-20T00:23:00.174Z] Information: WebSocket connected to wss://localhost:44306/_blazor?id=vuY411dkAsPan4fQrNN3aw.
blazor.server.js:1 [2020-07-20T00:23:00.175Z] Debug: The HttpConnection connected successfully.
blazor.server.js:1 [2020-07-20T00:23:00.175Z] Debug: Sending handshake request.
blazor.server.js:1 [2020-07-20T00:23:00.176Z] Information: Using HubProtocol 'blazorpack'.
blazor.server.js:1 [2020-07-20T00:23:00.182Z] Debug: Server handshake complete.
blazor.server.js:1 [2020-07-20T00:23:00.182Z] Debug: HubConnection connected successfully.
blazor.server.js:1 [2020-07-20T00:23:00.327Z] Information: Close message received from server.
blazor.server.js:1 [2020-07-20T00:23:00.329Z] Debug: HttpConnection.stopConnection(undefined) called while in state Disconnecting.
blazor.server.js:1 [2020-07-20T00:23:00.332Z] Error: Connection disconnected with error 'Error: Server returned an error on close: Connection closed with an error.'.
e.log @ blazor.server.js:1
e.stopConnection @ blazor.server.js:1
transport.onclose @ blazor.server.js:1
e.close @ blazor.server.js:1
e.stop @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
a @ blazor.server.js:1
Promise.then (async)
c @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
M @ blazor.server.js:1
e.stopInternal @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
M @ blazor.server.js:1
e.stop @ blazor.server.js:1
e.processIncomingData @ blazor.server.js:1
connection.onreceive @ blazor.server.js:1
i.onmessage @ blazor.server.js:1
blazor.server.js:1 [2020-07-20T00:23:00.333Z] Debug: HubConnection.connectionClosed(Error: Server returned an error on close: Connection closed with an error.) called while in state Connected.
blazor.server.js:1 Uncaught (in promise) Error: Server returned an error on close: Connection closed with an error.
    at e.processIncomingData (blazor.server.js:1)
    at e.connection.onreceive (blazor.server.js:1)
    at WebSocket.i.onmessage (blazor.server.js:1)
e.processIncomingData @ blazor.server.js:1
connection.onreceive @ blazor.server.js:1
i.onmessage @ blazor.server.js:1
Promise.then (async)
c @ blazor.server.js:8
a @ blazor.server.js:8
Promise.then (async)
c @ blazor.server.js:8
(anonymous) @ blazor.server.js:8
r @ blazor.server.js:8
E @ blazor.server.js:8
(anonymous) @ Eol:12448
blazor.server.js:19 [2020-07-20T00:23:03.338Z] Error: TypeError: window.Blazor.reconnect is not a function
e.log @ blazor.server.js:19
(anonymous) @ blazor.server.js:19
(anonymous) @ blazor.server.js:19
(anonymous) @ blazor.server.js:19
a @ blazor.server.js:19
Promise.then (async)
c @ blazor.server.js:19
(anonymous) @ blazor.server.js:19
r @ blazor.server.js:19
e.attemptPeriodicReconnection @ blazor.server.js:19
e @ blazor.server.js:19
e.onConnectionDown @ blazor.server.js:19
(anonymous) @ blazor.server.js:8
(anonymous) @ blazor.server.js:1
e.completeClose @ blazor.server.js:1
e.connectionClosed @ blazor.server.js:1
connection.onclose @ blazor.server.js:1
e.stopConnection @ blazor.server.js:1
transport.onclose @ blazor.server.js:1
e.close @ blazor.server.js:1
e.stop @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
a @ blazor.server.js:1
Promise.then (async)
c @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
M @ blazor.server.js:1
e.stopInternal @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
M @ blazor.server.js:1
e.stop @ blazor.server.js:1
e.processIncomingData @ blazor.server.js:1
connection.onreceive @ blazor.server.js:1
i.onmessage @ blazor.server.js:1
blazor.server.js:19 [2020-07-20T00:23:06.346Z] Error: TypeError: window.Blazor.reconnect is not a function
e.log @ blazor.server.js:19
(anonymous) @ blazor.server.js:19
(anonymous) @ blazor.server.js:19
(anonymous) @ blazor.server.js:19
a @ blazor.server.js:19
Promise.then (async)
c @ blazor.server.js:19
a @ blazor.server.js:19
Promise.then (async)
c @ blazor.server.js:19
(anonymous) @ blazor.server.js:19
r @ blazor.server.js:19
e.attemptPeriodicReconnection @ blazor.server.js:19
e @ blazor.server.js:19
e.onConnectionDown @ blazor.server.js:19
(anonymous) @ blazor.server.js:8
(anonymous) @ blazor.server.js:1
e.completeClose @ blazor.server.js:1
e.connectionClosed @ blazor.server.js:1
connection.onclose @ blazor.server.js:1
e.stopConnection @ blazor.server.js:1
transport.onclose @ blazor.server.js:1
e.close @ blazor.server.js:1
e.stop @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
a @ blazor.server.js:1
Promise.then (async)
c @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
M @ blazor.server.js:1
e.stopInternal @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
M @ blazor.server.js:1
e.stop @ blazor.server.js:1
e.processIncomingData @ blazor.server.js:1
connection.onreceive @ blazor.server.js:1
i.onmessage @ blazor.server.js:1
blazor.server.js:19 [2020-07-20T00:23:09.353Z] Error: TypeError: window.Blazor.reconnect is not a function
e.log @ blazor.server.js:19
(anonymous) @ blazor.server.js:19
(anonymous) @ blazor.server.js:19
(anonymous) @ blazor.server.js:19
a @ blazor.server.js:19
Promise.then (async)
c @ blazor.server.js:19
a @ blazor.server.js:19
Promise.then (async)
c @ blazor.server.js:19
a @ blazor.server.js:19
Promise.then (async)
c @ blazor.server.js:19
(anonymous) @ blazor.server.js:19
r @ blazor.server.js:19
e.attemptPeriodicReconnection @ blazor.server.js:19
e @ blazor.server.js:19
e.onConnectionDown @ blazor.server.js:19
(anonymous) @ blazor.server.js:8
(anonymous) @ blazor.server.js:1
e.completeClose @ blazor.server.js:1
e.connectionClosed @ blazor.server.js:1
connection.onclose @ blazor.server.js:1
e.stopConnection @ blazor.server.js:1
transport.onclose @ blazor.server.js:1
e.close @ blazor.server.js:1
e.stop @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
a @ blazor.server.js:1
Promise.then (async)
c @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
M @ blazor.server.js:1
e.stopInternal @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
M @ blazor.server.js:1
e.stop @ blazor.server.js:1
e.processIncomingData @ blazor.server.js:1
connection.onreceive @ blazor.server.js:1
i.onmessage @ blazor.server.js:1
blazor.server.js:19 [2020-07-20T00:23:12.375Z] Error: TypeError: window.Blazor.reconnect is not a function
e.log @ blazor.server.js:19
(anonymous) @ blazor.server.js:19
(anonymous) @ blazor.server.js:19
(anonymous) @ blazor.server.js:19
a @ blazor.server.js:19
Promise.then (async)
c @ blazor.server.js:19
a @ blazor.server.js:19
Promise.then (async)
c @ blazor.server.js:19
a @ blazor.server.js:19
Promise.then (async)
c @ blazor.server.js:19
a @ blazor.server.js:19
Promise.then (async)
c @ blazor.server.js:19
(anonymous) @ blazor.server.js:19
r @ blazor.server.js:19
e.attemptPeriodicReconnection @ blazor.server.js:19
e @ blazor.server.js:19
e.onConnectionDown @ blazor.server.js:19
(anonymous) @ blazor.server.js:8
(anonymous) @ blazor.server.js:1
e.completeClose @ blazor.server.js:1
e.connectionClosed @ blazor.server.js:1
connection.onclose @ blazor.server.js:1
e.stopConnection @ blazor.server.js:1
transport.onclose @ blazor.server.js:1
e.close @ blazor.server.js:1
e.stop @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
a @ blazor.server.js:1
Promise.then (async)
c @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
M @ blazor.server.js:1
e.stopInternal @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
M @ blazor.server.js:1
e.stop @ blazor.server.js:1
e.processIncomingData @ blazor.server.js:1
connection.onreceive @ blazor.server.js:1
i.onmessage @ blazor.server.js:1
blazor.server.js:19 [2020-07-20T00:23:15.390Z] Error: TypeError: window.Blazor.reconnect is not a function
e.log @ blazor.server.js:19
(anonymous) @ blazor.server.js:19
(anonymous) @ blazor.server.js:19
(anonymous) @ blazor.server.js:19
a @ blazor.server.js:19
Promise.then (async)
c @ blazor.server.js:19
a @ blazor.server.js:19
Promise.then (async)
c @ blazor.server.js:19
a @ blazor.server.js:19
Promise.then (async)
c @ blazor.server.js:19
a @ blazor.server.js:19
Promise.then (async)
c @ blazor.server.js:19
a @ blazor.server.js:19
Promise.then (async)
c @ blazor.server.js:19
(anonymous) @ blazor.server.js:19
r @ blazor.server.js:19
e.attemptPeriodicReconnection @ blazor.server.js:19
e @ blazor.server.js:19
e.onConnectionDown @ blazor.server.js:19
(anonymous) @ blazor.server.js:8
(anonymous) @ blazor.server.js:1
e.completeClose @ blazor.server.js:1
e.connectionClosed @ blazor.server.js:1
connection.onclose @ blazor.server.js:1
e.stopConnection @ blazor.server.js:1
transport.onclose @ blazor.server.js:1
e.close @ blazor.server.js:1
e.stop @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
a @ blazor.server.js:1
Promise.then (async)
c @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
M @ blazor.server.js:1
e.stopInternal @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
(anonymous) @ blazor.server.js:1
M @ blazor.server.js:1
e.stop @ blazor.server.js:1
e.processIncomingData @ blazor.server.js:1
connection.onreceive @ blazor.server.js:1
i.onmessage @ blazor.server.js:1

_Layout.cshtml 在头部包含<base href="/">，在<body> 末尾包含：

<script src="_framework/blazor.server.js" autostart="false"></script>
<script>
    Blazor.start({
        configureSignalR: function (builder) {
            builder.configureLogging(1); // LogLevel.Information
        }
    });
</script>

我有 _Imports.razor 在根目录和在 Pages 文件夹中，包含

@using Microsoft.AspNetCore.Authorization
@using Microsoft.AspNetCore.Components
@using Microsoft.AspNetCore.Components.Authorization
@using Microsoft.AspNetCore.Components.Forms
@using Microsoft.AspNetCore.Components.Routing
@using Microsoft.AspNetCore.Components.Web
@using Microsoft.JSInterop
@using MyAppNamespace

Startup.cs 在ConfigureServices 中有services.AddServerSideBlazor();，Configure 说：
```
.MapRazorPages();
.MapBlazorHub();
.MapFallbackToPage("/_Host");
```

_Host.cshtml 位于 Pages 文件夹中，包含

@page "/blazor"
@{
    Layout = "_Layout";
}

<app>
    <component type="typeof(App)" render-mode="ServerPrerendered" />
</app>

根据控制台日志，从索引页面连接工作正常，但不适用于使用组件的另一个页面。

我显然缺少一些管道，但我不知道它是什么。我错过了什么？

更新：我尝试在索引页面中使用 blazor 组件，似乎客户端连接正常，但我看到同样的事情：页面呈现组件，然后连接关闭，并且没有尝试重新连接成功。

【问题讨论】：

我有这个问题。 aspnet 核心 3.1
你有什么运气吗？

标签： blazor

【解决方案1】：

你说：_Layout.cshtml 包含<href="/">

如果这不是拼写错误，请将其更改为 <base href="/">

【讨论】：

感谢您注意到我帖子中的错字！代码居然有：<base href="/">
所以，需要明确的是，这不是问题所在。为什么连接被关闭？

【解决方案2】：

在将复杂对象作为参数传递给我的组件时，我观察到了这种行为。

<component type="typeof(MyComponent)" render-mode="ServerPrerendered" param-Data="@myComplexObject" />

似乎组件标签助手只适用于简单类型参数。

对我来说，我可以通过将渲染模式设置为 Static 来解决这个问题，但这对每个人来说都不是一个好的解决方案。

【讨论】：