Why would the debugger not be stopping at a breakpoint in my ASP.NET application?

I’m trying to debug a large ASP.NET application.

I set a breakpoint on the first line in Page_Load in Default.aspx.cs.

When I start the application, my breakpoint briefly turns into a red round outline with an exclamation in it, then turns back into a regular breakpoint, then the application starts without ever stopping at my breakpoint.

MSDN tells me that this symbol means “the breakpoint location has not been loaded”. So how can I get the breakpoint location to load? It was working a couple weeks ago. What kinds of things could cause a breakpoint to “not be loaded”?

What can I do so that the debugger stops at my breakpoints again?

Addendum:

I still can’t get debugging to work by pressing F5, but I can start the website, then do debug/attach-process to get into debugging mode. If anyone knows why this would work but when I press F5 it would not work (the debugging buttons don’t even show up on F5), any ideas would be welcome.

Answers:

Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

Try doing a full rebuild on the application. Pay attention that it’s in the “Debug” configuration.

As far as I understand (but I’m not an expert in these things), this can happen when the debug info files (.PDB) are out of sync with the real compiled thing.

Method 2

People…. I found other solution for breakpoint dont stop.
In Attach to Process window on Visual Studio 2010 and using Framework 3.5, by default automatically determines the code types to debug (v2.0, v1.1, v1.0) and (v4.0).

Visual Studio gets confused and automatically determines 2.0 managed code as 4.0 managed code sometimes.

In this case you need to click in “Select…” button on “Attach to” field and select Manage (v2.0, v1.1, v1.0).

Regards

Method 3

VS Debug Problem with IE8

Since this is my first post on Weblogs, I decided to write about a problem that has been opened frequently on the ASP.NET official forum which is the VS debugger crashes with IE8.

I had answered the same problem 4 times, so I hope that some one will find this post very helpful if he is facing the same problem.

How could the VS debugger crash with IE8?

If you opened multiple instances of IE8 and you attempt to debug your project, you will mostly have the issue where the VS debugger just stops and ignores your break points!

Why was that?

IE 8 has a feature called Loosely-Coupled Internet Explorer (LCIE) which results in IE running across multiple processes.
http://www.microsoft.com/windows/internet-explorer/beta/readiness/developers-existing.aspx#lcie

Older versions of the Visual Studio Debugger get confused by this and cannot figure out how to attach to the correct process.

To overcome this issue, you need to disable the process growth feature of LCIE by following the below steps:

1) Open RegEdit
2) Browse to HKEY_LOCALMACHINE -> SOFTWARE -> Microsoft -> Internet Explorer -> Main
3) Add a dword under this key called TabProcGrowth
4) Set TabProcGrowth to 0

If you run into the same problem on Vista or newer, you will also need to turn off protected mode.

And then go ahead and start debugging your code 🙂

Method 4

You could also try the following:

1. Close the solution and visual studio.
2. Run iisreset /stop
3. Delete everything under C:windowsmicrosoft.netframeworkv2.0.50727Temporary ASP.NET Files. If you have issues deleting some of these files you may have a version of visual studio or it’s debugger still running.
4. Run iisreset /start
5. Open the solution in VS
6. Set the build to Debug
7. Run Rebuild all at the solution level
8. Hit F5

Method 5

If you’re using Visual Studio 2005 and IE8 I might have an explanation: IE8 introduced a new feature called Loosely-Coupled IE (LCIE) which causes known problems when debugging VS2005 ASP.NET applications. See this thread on SO for more details and some solutions.

It turned out all my debugging problems went away when I shut down all running instances of IE8 before I started a debugging run in my ASP.NET project.

Another reason I’m posting here is to share a blog I found that lists a large number of potential solutions to the ‘breakpoints not working’ problem. It’s nice because the blog lists in one place most of the solutions I found scattered about the Internet. Anyway the blog’s author is George P. Alexander; I’ll copy and paste the juicy parts here in case something happens to the article:

1. Using precision guided missiles: Delete the .pdb files in your obj and
   bin folders. Recompile. Run.
2. Carpet bomb all .dlls: Delete and reload all the referenced .dlls (Like
   your class projects)
3. Release a WMD: If #1 & #2 didn’t work, delete the contents of the very
   obj and bin folders itself so that
   all .pdbs and .dlls are annihilated.
   Reload the .dlls required and give it
   a shot.
4. VS.Net magic: Close VS.Net and restart. Rebuild. Run. Yes, it
   sometimes does work.
5. Windows magic: Shutdown your computer and restart. Rebuild. Run.
6. Execution mode: Make sure that VS.Net execution mode is set to
   “Debug” and not “Release”
7. Web.config settings: Make sure that the XML Element “compilation” tag in
   your web.config file has an attribute
   with debug = “true”. Only if this is
   enabled will web apps and services
   have their .pdb files generated with
   the .dlls
8. Project properties #1: Make sure that Project Properties –> Debug –>
   Enable “ASP.Net Debugging is true” or
   “Enable the Visual Studio Hosting
   Process” (depending on the version of
   VS.Net you are using).
9. Project properties #2: Make sure that Project Properties –>
   Configuration Properties –> Build –>
   “Generate Debugging Information” is
   set to “True”.
10. Wrong process attached: Your debugging session may not be attached
    to the right process. You may have to
    step-in to manually attach the
    process. This is possible with Web
    Services. The option to attach a
    process is within the debug menu.
11. Script and unmanaged code debugging: Can’t debug scripts or
    unmanaged code? Make sure that Project
    Properties –> Debug –> “Enable ASP
    Debugging” or “Enable Unmanaged
    Debugging” (depending on your version
    of VS.Net) is set to true.
12. @Page directive #1: Make sure that the AutoEventWireup attribute in your
    .aspx document’s @Page directive set
    to “true”.
13. @Page directive #2: Make sure that the Debug attribute in your .aspx
    document’s @Page directive set to
    “true”. If you do not find the
    attribute, it’s okay. By default it is
    true.
14. Rogue .DLLs: Make sure that you do not have another instance of the .dll
    running which lies else where from
    your intended Project path.

14.1 Rogue .dlls sleeper cell #1: Did you install your project .dll in the
GAC folder? You could be running the
.dll hosted in your GAC folder instead
of the one in your bin folder.
Remove/Uninstall the .dll from the GAC
and then try again.

14.2 Rogue .DLLs sleeper cell #2:

C:Documents and
Settings[UserName]VSWebCache[Machine
Name]:

Release a WMD (#3) on the folders that
are related to your project.

14.3 Rogue DLLs sleeper cell #3: .dlls from your project that are lying else
where but are instead referenced in
your project. You can find these out
by examining project properties. In
short, VS.Net is referring some other
.dll and not the one loaded in your
dev environment.

14.4 Rogue .DLLs sleeper cell #4: Hopefully you won’t have to play with
this folder by the time you finish
with the above points…

Introducing
C:WINDOWSMicrosoft.NETFramework[.Net
version]Temporary ASP.NET Files

This folder could contain older
versions of .dlls stored in your
Windows folder which might get
referenced while running from VS.Net.
If this happens, it sucks. You can
delete as many folders and contents as
you can PERTAINING TO YOUR PROJECT.
There might be read-only locks which
you would need to disable by closing
processes. This is more of a last
ditch effort. Don’t do this if you’ve
never played around with your Windows
folder. In most cases something done
above before this point usually does
fix it. So ideally, you don’t have to
read this point by the time you’re
done with the above pointers. And just
for the record, I do not recommend
anyone to explore this option or play
around with your Windows folder if you
do not have a Phd in Physics,
Mathematics, Windows and .Net.

Other tips:

1. Module Window: The module window can be viewed while your application
   is running from VS.Net (Debug –>
   Windows –> Modules). All modules from
   your project should be listed there.
   If your project’s .dll is listed and
   the status of the Symbols is “Symbols
   Loaded”, you’ve got no problem.

If it’s a message related to your .pdb
file, goto “Select Symbols” and the
appropriate .pdb file. You might have
to restart debugging or load VS.Net
again. The status should now change
to “Symbols Loaded”.
2. VS.Net Options: Tool –> Options –> Debugging In VS.Net 2005 onwards, there is one more node called
“Symbols” where you can ask VS.Net to
look for symbols. This can be accessed
via the Module Window when debugging
too.

Method 6

Did you set <compilation debug="true"> in your web.config?

Method 7

I had a similar problem with breakpoints not working and, at the same time, in the IIS Console I was not able to edit the configuration for my project, i.e. the Edit Configuration button was greyed out.
[To find the Edit Configuration button: Start | All Programs | Administrative Tools | Internet Information Services, then expand the required computer, expand Web Sites, expand Default Web Site, locate and right click on your required project, select Properties and then the ASP.Net tab.]
I discovered that in IIS, the ASP.Net version for my project was set to 4.0.30319. Once I set it to 2.0.50727, the Edit Configuration button became available (clickable) and my breakpoints worked again.

I also realised that it might be worth checking the ASP.Net version set in IIS for “Default Web Site” [in the IIS Console, expand Web Sites, right click on Default Web Site and select Properties then the ASP.Net tab], so that any new projects created in Visual Studio acquire the Default Web Site setting.

Method 8

I had this problem recently (WinXP, VS2003), and tried many of the solutions above with no success. Then, I realized that there were multiple versions of the .Net runtime installed.
So, I brought up IIS 5.1, located the proper virtual folder, went into properties and then the ASP.NET tab, and changed the ASP.NET version from 4.? to 1.1, and it appeared that this solved the problem. It could be that the solution is this, PLUS one or more of the things above.

Also, all of the above make up a “kitchen sink” of different things to try. This is like throwing a bunch of spaghetti noodles against the wall, hoping that some of them will stick.
And, some of these “solutions” may cause other problems in your program. For example, the suggestion of setting AutoEventWireup=”true” may cause some of your events to fire twice!!! (see http://support.microsoft.com/kb/814745).

Method 9

Always look for Solution Configurations to be Set As “Debug” for debugging.
It may change to Release configuration after publishing.

Method 10

For me, the Project Properties had been reset by another dev to use IIS Express and not my Local IIS with.
So the project ran OK but nothing was being hit.

Right click on the Project > Properties > Web > Servers – change to Local IIS.
I know this won’t work for everyone but hope this helps someone.

Method 11

1. Go to your solution properties.
2. Inside Configuration Properties,Set build configuration set to ‘Debug’ instead of ‘release’for all projects in your solution.
3. Click on Apply and then OK button.

Method 12

In my case, the issue ending up being related to both using full IIS (not Express) and having a debug build where it included full debug symbols but also had project properties, Build, Optimize code checked.

Under Express, this works fine, but under full IIS this doesn’t work. Visual Studio attaches to the w3wp process correctly, but it does not load symbols for the optimized dll. In Visual Studio you can go to Debug, Windows, Modules then scroll for the specific dll and see if under the Symbol Status column it shows Skipped Loading Symbols.. Right-click on it and select Load Symbols to make it work.

One additional setting that can affect this is if Visual Studio is set to only debug user code under Debug, Options and Settings, Debugging, General, Enable Just My Code. When optimized, the dlls will be marked as not user code when running under full IIS, so when Just My Code is enabled any breakpoints in them will be skipped. You can either set VS to debug non-user code or set the build to not optimize to allow breakpoints to be hit.

Method 13

This drove me nuts for a week until I finally noticed a missing setting.
This builds on Jay Riggs’s answer, but for Visual Studios 2010 instead of 2005.
In project properties -> Web -> Debuggers, make sure that the ASP.NET debugger is checked.

Method 14

Sounds silly, but put a breakpoint earlier in the process: maybe the process doesn’t reach the breakpoint.

Method 15

Just a little add from something that happened to me in C# WPF but I think that it applies here as well. I tried the above answers but none worked.

Code —> Thread —> Function START – breakpoint – END

That might not be your case but I hope that this might help someone. From my code I was launching a thread from which a launched an external function. So try as I might I could not get the breakpoint to work from the external function. And the behaviour (despite my rebuilding or changing options) was exactly what explained in the question.

So I had to move the breakpoint from the external function to the thread and that worked. When stopped I proceeded with F10-F11

Code —> Thread breakpoint —> Function START – END

Method 16

Debug=>Options=>General => Remove the check mark for “Enable Just My Code”

This worked for me

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0