'Why am I unable to Debug my ASP.NET website in Visual Studio?

I used to be able to attach to my w3wp process and Debug my web application, but this is not working anymore. I have no idea what changed to break this. I'm using Visual Studio 2008 SP1. And I'm debugging in IIS, not using ASP.NET's own server (i.e. I don't Run my project, I simply attach to a running process (w3wp).

My breakpoints simply have the "breakpoint will currently not be hit. The source code is different from the original version."

What I have tried:

Did a solution Clean.
Did a solution Rebuild.
Made sure that compilation debug=true in my web.config file.
Deleted the bin folder
Restarted Visual Studio
Restarted IIS
Restarted my Computer
Added a simple Response.Write to ensure that the latest DLL is being used. It is.
Made sure that Debug ASP.NET is checked in my project properties. It is.
Made sure that all my projects are compiled in my build configuration. They are.

But none of these help. I attach to w3wp, but my breakpoints never get hit.

Any ideas?

asp.net debugging

Solution 1:^[1]

I had this problem recently and I ended up first making sure Visual Studio was not running at all on the system.

Then went into this folder and deleted all its content:

C:\windows\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\

Solution 2:^[2]

Check your web.config for

<compilation debug="true">...

Solution 3:^[3]

When you "Attach to process", the Output window should show you (when showing output from "Debug") all the libraries it's loading, and where it's loading them from - for the dll's in your /bin folder these are usually copied to the \Temporary ASP.NET Files\root\ folder - where are yours being read from? Have you definitely cleared them out from there?

The only other things I can think of:

You've compiled your code in "Release" mode rather than "Debug" (not the web.config) from the Solution Configuration drop-down.
The symbol files (.pdb) are missing from your /bin folder.

On the "Build" tab of the project properties, you are in configuration "Active (Debug)", you haven't check "optimize code"?

If you click "Advanced..." on that tab, what value do you have for "Debug Info"? Is it "full" or "none"?

Responding to comment

You will find it harder to debug successfully if your code compiled in "Release" mode, and you'll often get the "source code is different" message when you've not rebuilt the symbols (.pdb files) after changes - but you say you've done a clean/rebuild, so that should cover that.

Yes, your output window will show all the framework dlls that you're referencing as well as your code - but you should see one file listed in there with the name of each project output - those are the ones to look at.

You don't have some post build event that moves files into the correct directory for your site do you that's silently failing?

Solution 4:^[4]

I also had this problem, solved it by changing the "Attach to" code type to Automatic on the "Attach To Process" dialog. (Previously I had this set to "Silverlight Code" due to debugging a different process... it can be easy to forget to change this back.)

Solution 5:^[5]

I know this issue has been open for some time, but I think it is the same as I experienced:

I could not debug my .aspx server side code. I had a working WepApp AnyCPU project and I wanted to link to some x86 dlls, so I created an x86 debug target. Did similar things, rebuilt, stopped the development web server, rebooted, clear temporary files, all to no avail.

Fixed the problem by changing the target folder to bin\ (was bin\x86\Debug).

Solution 6:^[6]

in the "Attach to process" dialog, click the checkbox (near the bottom) for "show processes from all users" and if you see two w3wp.exe processes, try the other one.

One should have a comments/description value of something like T-SQL, managed somethingoranother. This is the one you want.

Solution 7:^[7]

Are you running any add ins that could be affecting this? Or any tools that apply post build operations to the source code that the DLLs you start debugging with have been modified post build and it actually is correct that it's not the same source code so debugging won't work?

Also have tried resetting VS?

devenv.exe /resetsettings

Edit: if none of the information has aided you here, while painful it might be worth uninstalling and reinstalling VS and SP1. If you go through this and the issue is the same afterwards that atleast assures that the issue lies in either the web.config or the project settings.

Solution 8:^[8]

Did you check your assembly.cs file with this attribute

[assembly: Debuggable(DebuggableAttribute.DebuggingModes.IgnoreSymbolStoreSequencePoints | DebuggableAttribute.DebuggingModes.Default)]

After reflecting a optimized code you will probably get this. So you must remove this to be able to debug again.

Solution 9:^[9]

I faced the same issue. The w3wp process took a lot of memory and did not want to be reset on web application publishing.

Press Ctrl+Alt+Delete > Go to "Processes" tab > find w3wp process and kill it. Run the app again (if this is an mvc app, just go to a related url to automatically recreate w3wp process).

Warnings will disappear after that.

Solution 10:^[10]

I have tried all the below options in my Visual Studio 2013 Update 4.

Reset IIS
Clean solution and rebuild
Delete the friles from temporary folder C:\Windows\Microsoft.Net\Framework...\Temporary ASP.NET files
Check whether the compilation tag is debug or not

But none of them worked, here I am listing down the two things which worked for me.

Disabling the "Just My Code" option Tools ->Options -> Debugging -> General -> Uncheck Enable Just My Code.
Edit the web.config file and save (You can always create a space in any line in web.config, that will do)

Please be noted that this solution can be Visual Studio version specific, and the both fix worked for me in my Visual Studio 2013 Update 4.

Solution 11:^[11]

I have had this problem for a while and found my solution on the MS forum (link below). Debug Diagnostic Tool was the culprit for me, but I did not have to uninstall it. I had a crash rule set up for the w3wp process and I simply removed that rule and restarted everything.

Microsoft Forum for Unable to attach error

Solution 12:^[12]

On OpenVMS we just used to:

Compile/Debug then Link/Debug

and that was it! Simples!!

but seriously, make sure the file you have your Debugger.Break line in, has 'Copy always' set in its Properties before re-building

Solution 13:^[13]

I was using the Visual Studio extension VSCommands to attach the debugger (convenient). However, IIS Express was running, and I guessed it might be interfering. Sure enough, when I closed IIS Express, suddenly I was able to debug again.

Joy ensued.

Solution 14:^[14]

In my case I had a Console Application the hosted web page in .Net Framework 4.6.1. When I added a Debug to Conditional compilation symbols, it started to work:

Solution 15:^[15]

Make sure that "Current Page" and not "Don't open a page. Wait for a request from an external application." is checked under Properties->Web->Start Action.

Solution 16:^[16]

add this code in your .csproj file

   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|AnyCPU'">
    <DefineConstants>DEBUG;TRACE</DefineConstants>
    <Optimize>false</Optimize>
    <DebugType>full</DebugType>
    <DebugSymbols>true</DebugSymbols>
  </PropertyGroup>

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution	Source
Solution 1	Gautam
Solution 2	citronas
Solution 3
Solution 4	Mr. Bungle
Solution 5	Digital Chilli
Solution 6	David Fox
Solution 7
Solution 8	HoKy22
Solution 9	Anton Lyhin
Solution 10	Sibeesh Venu
Solution 11	Pam
Solution 12	Reg Hammond
Solution 13	Community
Solution 14	Mik
Solution 15	NegativeFeedbackLoop
Solution 16	Noureddine AMMAR

'Why am I unable to Debug my ASP.NET website in Visual Studio?

Solution 1:[1]

Solution 2:[2]

Solution 3:[3]

Solution 4:[4]

Solution 5:[5]

Solution 6:[6]

Solution 7:[7]

Solution 8:[8]

Solution 9:[9]

Solution 10:[10]

Solution 11:[11]

Solution 12:[12]

Solution 13:[13]

Solution 14:[14]

Solution 15:[15]

Solution 16:[16]