The breakpoint will not currently be hit. No symbols have been loaded for this document in a Silverlight application

Right click on solution --> Properties

Look under Common Properties --> Startup Project

Select multiple startup projects

select Start action on the projects you need to debug.

I had the same issue and after googling I found two typical solutions for this:

1. Make sure the Silverlight debugger is activated in the .Web project. Open up the project properties and select the Silverlight debugger under the "Web" tab.

2. Restart Visual Studio and delete all bin and obj folders.

But none of these worked for me. Then someone mentioned far down a thread to try using IE as the browser instead. This made debugging and breakpoints work again!

Edit:

Later I have struggled with IE9 not working, because it attaches to the wrong process. Instead of manually attaching to the correct IE process every time, I found a neat trick:

• Right-click one of the generated pages in the .Web project (.html or .aspx)
• Click "Browse with..."
• Set IE as default browser (will only affect Visual Studio's choice of browser)

Now, Visual Studio will launch IE when running the .Web project and attach to the correct process. That should do it.

Whenever I've had this particular error come up, it's turned out that the folder that Visual Studio is loading assemblies from is different from the folder the web-application is running from.

That is, the application server is running the application from

C:\dev\MyApplication\bin 

but Visual studio is debugging from

C:\dev\MyOtherApplication\bin (or something along those lines, anyway).

Note - for various reasons, I do my debugging with IIS as the application host instead of the dinky standalone gizmo that most people use. This could influence the usefulness of my answer!

Update:

For IIS the application server directory (i.e. C:\dev\MyApplication above) is the physical directory configured for the web application - this can be controlled by changing basic settings for the app.

For Visual studio the debugging directory (i.e. C:\dev\MyOtherApplication above) is the directory in which your svc files are found, usually the same directory as your csproj project file.