Aspnetcore: Blazor Server-side doesn't start with Windows Authentication on Chrome

[GerardSmit]

Describe the bug

The server-side Blazor application doesn't start when the authentication is set to Windows Authentication in Google Chrome. Creating an application without authentication works fine.

To Reproduce

Steps to reproduce the behavior:

1. Create a new Blazor server-side application with Windows Authentication
2. Start the application in IIS Express and open the application in Chrome.
3. You'll see the pre-rendered page and in the top-right the username of the current Windows user is shown: Hello, DOMAIN\user!.
4. Go to the page 'Counter'.
5. When you try to click the button 'Click me', nothing happens.

Additional context

I've tested in the following browsers with Windows Authentication enabled:

| Browser | Is working? |
|-------------------|-------------|
| Chrome | No |
| Internet Explorer | Yes¹ |
| Edge | Yes |
| FireFox | Yes |

¹ IE only works with https://github.com/Daddoon/Blazor.Polyfill added.

---

Some points that I found that might be handy:

1. By removing the line Html.RenderStaticComponentAsync<App>() in _Host.cshtml you'll notice that the page is white. The content that you see is pre-rendered.
2. Chrome and Internet Explorer does authenticate automatically but FireFox and Edge does not
   (I need to provide my username and password).
3. In Chrome, the WebSocket connection is established:
   
   but no data was sent:
   
4. In FireFox everything works fine:
   

---

> dotnet --info:
.NET Core SDK (reflecting any global.json):
 Version:   3.0.100-preview8-013656
 Commit:    8bf06ffc8d

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.17763
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\3.0.100-preview8-013656\

Host (useful for support):
  Version: 3.0.0-preview8-28405-07

> Visual Studio:
Microsoft Visual Studio Enterprise 2019 Preview
Version 16.3.0 Preview 2.0

> IIS
IIS Express 10.0.18362.1

> Google Chrome
Version 76.0.3809.132 (Official Build) (64-bit)

[mkArtakMSFT]

Thanks for contacting us, @GerardSmit.
We are unable to reproduce this issue, which indicates something is probably wrong on your end. You may need to look for errors in your browser dev console.

[GerardSmit]

I've checked the console but there is no error:

I cleared my cookies, site cache, local/session storage with no success. I tried the application in Incognito (so extensions wont load) but it still doesn't work. However when I open Chrome in the Guest mode the application works fine:

It seems there is something wrong with my account in Chrome, which is weird because it shouldn't affect the application at all.

That being said the issue isn't coming from Blazor. I thought I tried everything before creating this issue but I never expected it to be something like this. I'm sorry for the false report.

[GerardSmit]

Alright, found the problem.

After resetting Chrome (removing all settings and extensions) the application works. After re-enabling the extensions the application stopped working. It seems the extension "Tampermonkey" is causing problems, even in Incognito while it doesn't have access to Incognito.

[GerardSmit]

Reported in the Chromium bug tracker: https://bugs.chromium.org/p/chromium/issues/detail?id=998693

[mkArtakMSFT]

Thanks for information, @GerardSmit. Good to know. Hope this will help others in community too.

[coreyjthompson]

THANK YOU THANK YOU THANK YOU!!!!!!! I thought I was going nuts. Same issue but different extension. Didn't even consider the extensions being the issue until seeing your posts, especially since its happening in Incognito for me, also! I had to switch over to Edge just to test this last month or so.

[martshep]

While I understand that this failure is a chrome issue and not a blazor issue, the user experience when this occurs is very confusing. Would it be possible for Blazor to put up a warning when the SignalR connection to the server can't be established or is taking a really long time to establish, similar to the way that it displays an overlay if the connection is lost?

By the way, there are a few chrome extensions that cause this issue including, Requestly and Tampermonkey.

As a workaround for now, it is possible to change the RenderMode to Server to switch off pre-rendering and add something like the following to _Host.cshtml so that at least a user experiencing this issue gets a sensible error message rather than an application that doesn't respond to anything:

<div id="loading" style="position:absolute; visibility: hidden">
    <p>Error connecting to server....</p>
    <p>NOTE: If you are using Chrome and are seeing this then try a different browser or disable your plugins.</p>
</div>
<script type="text/javascript">
function showLoadingDiv() {
  document.getElementById("loading").style.visibility = "visible";
}
setTimeout("showLoadingDiv()", 10000); 
</script>

<app>
    @(await Html.RenderComponentAsync<App>(RenderMode.Server))
</app>

[GerardSmit]

Information for the participants: This issue has been fixed in Chrome 79, which is the next version of Chrome and will be released tomorrow (10 December).