Debugging Blazor Applications



We will be discussing how to debug both a server side Blazor application as well as a Client-side Web Assembly application.

Client-Side Web Assembly


To debug this type of application we will be using the browser tools to access the C# code.  As of this post, only Chrome supports debugging the web assembly client application.  Microsoft Edge can be used, but it just fires up a chrome instance to debug with.

Steps to debug:

      1.  Create a client-side web assembly application from the standard Blazor templates that are provide with Visual Studio or Visual Code
      2. Run application in Chrome
      3. Press F12
      4. You will see a comment to press Shift – Alt – D to debug
      5. Make sure you click on the actual Blazor application
      6. Press Shift-Alt-D
       7. A new browser tab will be displayed.
a.       If you do not see any errors, congratulation you are good to go.  Jump to step 8.
b.       If you see this error, Follow the steps below


c.       You need to copy the URL highlighted.  Please note that your URL will be different, and you need the listed for your projects.
d.       Close ALL the Chrome browsers you have open
e.       Go to the task manager and look for any Chrome related process running and kill those
                                                               i.      All chrome processes must be stopped to get this to work
f.        Press Win+R
g.       Paste in the URL and press enter
h.       Press Shift-Alt-D
      8. A new developer tab will be displayed
      9. Go to source
a.       Select the file:// node and expand
b.       Expand the “Pages” node
c.       Click on Counter.razor
d.       You should be able to see your C# code.


      10.   Set a break point on currentCount++
      11.   Go to the Counter page in the application
      12.   Click the “Click me” button and see the browser hit the break point
      13.   You can now step through the code like any other client-side debugging session.

 Server-side Application

The server side is much easier to debug.  You debug it like a normal server-side application.

Steps to Debug

       1.       Create a client-side web assembly application from the standard Blazor templates that are provide with Visual Studio or Visual Code
       2.       Run application in Chrome
       3.       In Visual Studio
a.       Set a break point on the currentCount++ line.
       4.       Go to the Counter page in the application
       5.       Click the “Click me” button and see the browser hit the break point

       6.       You can now step through the code like any other Visual Studio debug session.

Following this steps you should be able to debug either type of Blazor application.  I have found if I can walk the code it make things so much easier to understand.


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