If you're developing using ASP.NET MVC in Visual Studio, you may sometimes encounter a yellow warning bar while debugging stating:
"The source code is different from the original version."
This warning typically occurs when you are attempting to break or step into code, and Visual Studio is unable to properly match the source code it is currently viewing with the compiled assembly that it is debugging.
This can be really annoying, particularly when you are certain that you have saved your changes. In this article, we will outline why this happens and guide you through the process of fixing it.
What causes the Yellow Debugger Warning
This warning appears because the compiled DLL or PDB (debug symbols) which Visual Studio is referring to does not reflect your current source code. This can occur because of:
Code changes after the last build
Visual Studio referring to cached or outdated compiled files
Debugging against a deployed or published version which is outdated
Symbol files not being generated or loaded properly
How to fix this Issue
Follow these steps to debug the mismatch and resume smooth debugging.
1. Clean and Rebuild the Solution
A simple rebuild usually takes care of the problem.
In Visual Studio, navigate to:
Build > Clean Solution
Then: Build > Rebuild Solution
This makes Visual Studio recompile everything and refresh the binaries and symbols.
2. Delete Temporary Files
Visual Studio occasionally uses old compiled files.
Close Visual Studio
Delete the following directories manually from your project directory:
/bin
/obj
.vs (optional but useful in case of stubbornness)
Then close the solution and recompile it.
3. Check Debug Configuration
Make sure the project is compiled in Debug mode and is producing debug info.
Navigate to: Project > Properties > Build
Ensure the configuration is set to Debug
Ensure Define DEBUG constant is checked
Click Advanced.
Set Debug Info to: full.
Make sure Optimize code is unchecked
4. Inspect the Modules Window
If you don't know which DLL is loaded, look at the Modules window.
During debugging, do the following:
Debug > Windows > Modules
Search for your project's DLL (e.g., MyApp.dll)
Verify the Symbol Status — it should read:
Symbols loaded or
Symbols loaded from. (proper path)
Otherwise, your PDB file could be missing or out of date.
5. Restart IIS / IIS Express
If you're running IIS or IIS Express, sometimes they cache out-of-date files.
Stop and restart the server.
For IIS, execute:
iisreset
For IIS Express, stop all instances running and re-enable debugging.6. Turn off "Just My Code" (Optional)
This option can get in the way of debugging.
Go to: Tools > Options > Debugging
Uncheck "Enable Just My Code"
Also, select "Require source files to exactly match the original version" for more rigorous debugging.
Tips :
Sometimes a complete reset is what's needed:
Close Visual Studio.
Remove: .vs/, bin/, obj/
Open the solution again.
Rebuild the whole project.
This flushes out stale caches and makes Visual Studio recreate everything from scratch.
Close Visual Studio.
Remove: .vs/, bin/, obj/
Open the solution again.
Rebuild the whole project.
This flushes out stale caches and makes Visual Studio recreate everything from scratch.
If still not working you may try this :
Go to Tools >>option
s
Now select debugging mode
and now select General and you see right side option as highlighted in below snippet. Now need to uncheck it .
🙏 Thank You for Reading!
Thank you for taking the time to read this blog!
If you have any questions or need help with something, feel free to drop a message in the comments or contact section. I’ll get back to you as soon as possible.
Happy Learning! 😊