global.asax breakpoint not hit - asp.net

Question

I have some code in my ASP.NET app in C# that's in the Global.asax.cs code file. In the Application_Start, Session_Start and Application_Begin Request I have set some breakpoints. However none of these are ever hit. I'm working on my local machine with VS8.
Here's what I've tried:
Stopped the ASP Dev Server
Deleted all ASP.NET Temporary files
Created new Global.asax
Closing VS and opening back up
Clean and Rebuild project
Upon trying my after these, the breakpoints will not hit.
Any ideas why this might be?

Answer 1

I've run into this same problem. I'm assuming you are using your local IIS instead of the VS Development Server. If this is the case, you won't be able to debug/Step through this code in the Global.asax.cs file because by the time the debugger has attached, this code has already executed in IIS. However, if you use the Dev server, you have the ability to get to this code as the debugger will already be attached.
So, Change the server in your project properties to use the Visual Studio Development Server.
This can be found by right clicking your project within Visual Studio > Project Properties > Web tab > Use Visual Studio Development Server.

Answer 2

What helped me was to add:
System.Diagnostics.Debugger.Break(); to that Application_Start() method.

Answer 3

On a project I was working on, the "Start external program" option was selected in the tab:
Visual Studio > Project Properties > Web
This was causing the breakpoints to not be hit.
Changing "Start Action" to "Current Page" fixed this problem for me.

Answer 4

As metioned in another answer, the Global.asax code will run before the debugger gets chance to attach. To get around that you can start debugging, then go into IIS and Stop/Start the Application which should then have the debugger pick up the restart.

Answer 5

If you do not want to use Visual Studio Development Server and use IIS, you can do the following (tested in VS2015 Professional)
1) Application pool in a running state - make sure that used Application Pool is running by accessing a page from your Web app (it may be stopped due to a Idle timeout).
2) Attach to process - Ctrl-Alt-P or Debug -> Attach to Process -> lookup your w3wp process that corresponds to your application.
Attach to process can be greatly sped up by using ReAttach extension which creates shortcuts to recently attached processes.
3) Application pool recycle - make sure that the application pool recycles by either entering IIS and recycling it or even faster, by entering web.config, making a no-effect change (put some blank outside of tags) and saving it
4) Start debugging - Perform a request to any page from your web application to force its initialization. You should be able to place and hit breakpoints from any of the startup methods in the Global.asax
protected void Application_Start()
void Application_BeginRequest(Object sender, EventArgs e)
protected void Session_Start(object sender, EventArgs e)

Answer 6

I had this issue twice. The first project this happened to me, I went to Project Properties->Build->Advanced... and selected "full" from the Debug Info dropdown.
The second time, the breakpoints in my global.asax we're not being hit but it gave this warning if I hovered over the breakpoint: "The source code is different from the original version."
I finally figured out that in this case, I had made a backup copy of this project to preserve the code and was working with the copy. Even though it was in a different folder, it was still using the dll for the virtual directory of the original: http://localhost:4952/
So I changed that in Project Properties->Web->Project URL. I just changed the port to http://localhost:49523/ and it worked.
It prompted me to create the virtual directory, I said yes and haven't had any problems with breakpoints since.