Blazor Server - the circuit failed to initialize

user_13667748 0
Viewed 2010

I have published the BlazorApp1 app created by the VS2019 Blazor template to a production server. Since it is a sub-site, I made 3 changes:

  1. in _Host.cshtml replaced the base tag with <base href="/BlazorApp1/" >
  2. in Startup.cs added app.UsePathBase("/BlazorApp1")
  3. in web.config, changed the hostingModel to outofprocess and stdoutLogEnabled to true

When navigating to the site I almost always get the following error:

Unhandled Exception Page must be reloaded

This is displayed in the browser console: (replaced my site with contoso)

[2020-06-02T18:39:49.445Z] Information: Normalizing '_blazor' to 'http://www.contoso.com/BlazorApp1/_blazor'. blazor.server.js:1:5212
[2020-06-02T18:39:49.936Z] Information: WebSocket connected to ws://www.contoso.com/BlazorApp1/_blazor?id=5yq6pI_jo1ByPZtskEjjmw. blazor.server.js:1:5212
[2020-06-02T18:39:50.132Z] Error: The circuit failed to initialize. blazor.server.js:15:27309
    log http://www.contoso.com/BlazorApp1/_framework/blazor.server.js:15
    C http://www.contoso.com/BlazorApp1/_framework/blazor.server.js:8
    S http://www.contoso.com/BlazorApp1/_framework/blazor.server.js:8
    invokeClientMethod http://www.contoso.com/BlazorApp1/_framework/blazor.server.js:1
    invokeClientMethod .../BlazorApp1/_framework/blazor.server.js:1
    processIncomingData .../BlazorApp1/_framework/blazor.server.js:1
    onreceive .../BlazorApp1/_framework/blazor.server.js:1
    onmessage .../BlazorApp1/_framework/blazor.server.js:1
[2020-06-02T18:39:50.141Z] Information: Connection disconnected. blazor.server.js:1:5212
Error: Invocation canceled due to the underlying connection being closed. blazor.server.js:1:20001

I can't find any other clues about what's happening. There are no exceptions shown in the log.

blazor asp.net
2 Answers

The problem was resolved by using only lowercase characters in the <base> tag:

  <base href="/blazorapp1/" >
user_136677480

It has just happened to me as well, but I had the base tag specified correctly. This error can also occur in a rare case when you have ambiguous constructors defined for one of your dependency injected services if both match all the parameters (possibly by accident due to inheritance). The verbose log won't point to that issue. Be aware that purposeful creation of multiple constructors for dependency injected services is considered an anti-pattern.

user_37838520
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