title: Unable to debug Blazor hosted webassembly 3.2.0 from Visual Studio 2019 16.6.2
body: <p>I have Visual Studio 2019 16.6.2 installed, along with the .NET Core 3.1.301 SDK and all the necessary Blazor templates.</p>
  <p>If I create a brand new Blazor WebAssmbly application, I can run it from Visual Studio by pressing <kbd>Ctrl</kbd>+<kbd>F5</kbd> and it opens a new tab on my active browser window and starts fine.</p>
  <p>But when I press <kbd>F5</kbd>, a new, separate browser window is opened (which is midly annoying), but the page remains at <code>about:blank</code> for a while until an error message appears in Visual Studio:</p>
  <pre><code>Failed to launch debug adapter.  Additional information may be available in the output window.
  
  Unable to launch browser: 
  &quot;Could not open wss://localhost:5001/_framework/debug/ws-proxy?browser=wsAFFlocalhostA50821FdevtoolsFbrowserFceed3b95-58ac-470a-b10c-5d139cfd7117&quot;: timeout after 60000ms
  </code></pre>
  <p>Whether the Blazor WebAssembly application is &quot;Hosted&quot; or not doesn't make a difference.</p>
  <p>I've followed the steps in the <a href="https://docs.microsoft.com/en-gb/aspnet/core/security/enforcing-ssl?view=aspnetcore-3.1&amp;tabs=visual-studio#troubleshoot-certificate-problems" rel="noreferrer">Enforce HTTPS in ASP.NET Core</a>, but that made no difference.</p>
  <p>If, while waiting for the <code>about:blank</code> window to crash, I manually open the client side url on a browser tab, the app loads and the debugger breakpoints are hit.
  During the short while before it goes on to crash, if I hit <kbd>Shift</kbd>+<kbd>Alt</kbd>+<kbd>D</kbd> I <em>always</em> get the following error:</p>
  <pre><code>Unable to find debuggable browser tab
  Could not get a list of browser tabs from http://127.0.0.1:9222/json. Ensure your browser is running with debugging enabled.
  
  Resolution
  
  If you are using Microsoft Edge (80+) for your development, follow these instructions:
  Press Win+R and enter the following:
  
  msedge --remote-debugging-port=9222 --user-data-dir=&quot;C:\Users\sergi\AppData\Local\Temp\blazor-edge-debug&quot; --no-first-run https://localhost:44372/
  </code></pre>
  <p>I get this each and every time, no matter how often I run the command (having closed all browser instances, rebooted, etc).</p>
  <p>This happens in both Edge 84 (Edgium) and Chrome.</p>
  <p>I should be able to create a new Blazor WebAssembly app and hit <kbd>F5</kbd> on Visual Studio out of the box. What am I missing?</p>
  <h3>UPDATE</h3>
  <p>I've just tried using &quot;old Edge&quot; (EdgeHtml) and Firefox as the debug browser in Visual Studio, and both work as expected (meaning that the application at least starts up when pressing <kbd>F5</kbd>). The problem apears to be both Chromium-based browsers then...</p>
  <h3>UPDATE 2</h3>
  <p>@JamesHancock posted an easy enough workaround in the comments. For a full resolution (and explanation), <a href="https://github.com/dotnet/aspnetcore/issues/22911" rel="noreferrer">I've logged a Github issue</a> with the ASP.NET Core team.</p>