Visual Studio breakpoints not being hit

Question

I'm working with an ASP.NET MVC project that seems to be having some issues when attaching to the IIS process (w3wp.exe). I'm running the solution and IIS 8.5 on my own local machine so I wouldn't think that this has anything to do with our network. What's strange to me is that I'm able to hit the breakpoints on any other solution I debug locally.

The issue I'm having exactly is that the breakpoints turn to red, hollow circles and never get hit. Usually the fix for this is a Clean/Rebuild of the solution but this hasn't worked. I've confirmed the code is being updated by adding "throw new Exception" to a page and ensuring it shows the exception. Again, this problem is only happening with this one solution. Any other solution I run the debugger with works fine. I've also tried restarting the app pool, the website, IIS, and also my computer.

A few of the articles I read mentioned that anti-virus programs can block a remote debugger from accessing the process. However, the entire setup is contained on my local machine so it doesn't sound like that would be the issue. It does concern me a bit though because we recently hired a new IT guy that's been making a lot of changes to everyone's machine.

One other point to add that's unique about this web application is the binding in IIS. The binding is "*" in order to leverage some custom functionality related to subdomains.

In the meantime, I'll continue to look for a solution but if anybody has any ideas what may be causing this one solution to not debug properly I'd really appreciate it.

EDIT: Found a solution that suggested deleting the ASP.NET temporary files. No luck.

Answer 1

I struggled forever trying to fix this. Finally this is what did it for me.

Select Debug->Options->Debugging->General

Tick Enable .NET Framework source stepping.

(This may be all you need to do but if you are like me, you also have to do the ones stated below. The below solution will also fix errors where your project is loading old assemblies/.pdb files despite rebuilding and cleaning.)

Select Tools -> Options -> Projects and Solutions -> Build and Run,

Untick the checkbox of "Only Build startup projects and dependencies on Run",

Select Always Build from the "On Run, when project are out of date" dropdown.

Answer 2

Enable 'Managed Compatibility Mode'. Go to Tools->Options->Debugging and enable Managed Compatibility Mode.

Answer 3

In Visual Studio 2017 you need to make sure you're not in release configuration mode.

1. Open the build menu ddl
2. Click configuration manager
3. Change from 'release' to 'debug'

Answer 4

Right click on your project, then left click Properties, and select the Web tab.

Verify whether the correct server is selected for your case:

• IIS Local

• IIS Express

Answer 5

I had the same issue in a Xamarin.Forms project. The fix was manually converting the PCL from .NET 4.6 to .NET Standard 2.0.

Answer 6

If anyone is using Visual Studio 2017 and IIS and is trying to debug a web site project, the following worked for me:

1. Attach the web site project to IIS.
2. Add it to the solution with File -> Add -> Existing Web Site... and select the project from the inetpub/wwwroot directory.
3. Right-click on the web site project in the solution explorer and select Property Pages -> Start Options
4. Click on Specific Page and select the startup page (For service use Service.svc, for web site use Default.aspx or the custom name for the page you selected).
5. Click on Use custom server and write

http(s)://localhost/(web site name as appears in IIS)

for example: http://localhost/MyWebSite

That's it! Don't forget to make sure the web site is running on the IIS and that the web site you wish to debug is selected as the startup project (Right-click -> Set as StartUp Project).

Original post: How to Debug Your ASP.NET Projects Running Under IIS