Debugger not working for Debugging Extensions in Visual Studio 2026

Question

Debugger not working for Debugging Extensions in Visual Studio 2026

Devesh Ketan Patel 0

I am not able to debug my Extensions since I have moved to Visual Studio 2026.
When I start debugging and check the Symbol File that is being currently loaded for my Extension, it is coming from the Release path, i.e., it is loading the release .dll which hinders the debugging experience.
I have attached the source.extension.vsixmanifest and TWVSSCM.csproj as txt files and the screenshot for which Symbol File is getting picked up.

source.extension.vsixmanifest.txt

Symbol_File_Screenshot.png

TWVSSCM.csproj.txt

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2 answers

Your answer

Answer 1

In Visual Studio 2026, debugging an extension still relies on the same core mechanisms: the experimental instance, correct build configuration (Debug), and correct symbol (.pdb) and source loading. The behavior described—symbols loading from the Release output—indicates that the debugger is attaching to a different DLL than the one built by the active Debug configuration, or that symbol search paths are resolving to the Release build first.

Use the following steps to force the debugger to load the correct Debug symbols and DLL for the extension.

Start debugging the extension in the experimental instance

Open the extension project.
Set a breakpoint in the extension code (for example, in the InitializeServices method of the main Extension-derived class).
Start debugging with Debug > Start Debugging (F5). This launches the Visual Studio Experimental Instance where the extension is loaded.
Perform the actions in the experimental instance that activate the extension so the module is actually loaded.

Verify and correct symbol loading while debugging

In the main (debugger) Visual Studio instance, open the Modules window:
- Debug > Windows > Modules (or Ctrl+Alt+U).
Locate the module (DLL) for the extension in the list.
Check the Path column to confirm whether the loaded DLL is coming from the Debug or Release output folder.
Check the Symbol Status and Symbol File columns to see which .pdb is loaded.
Right‑click the module and use:
- Symbol Load Information to see exactly where the debugger searched for symbols and which .pdb it loaded.
- Load Symbols to force reloading from the configured symbol locations.
- If the wrong .pdb is loaded, use Load Symbols and then browse to the Debug output folder for the extension and select the correct .pdb.
- After loading the correct .pdb, right‑click again and choose Always Load Automatically so future sessions use this symbol file automatically.

Fix symbol search paths so Debug is preferred

Open Tools > Options.
Go to All Settings > Debugging > Symbols.
Under Symbol file (.pdb) locations:
- Remove or disable any paths that point to Release output folders for the extension.
- Add the Debug output folder of the extension project (for example, the bin\Debug path) as a symbol location.
- Ensure the Debug folder entry is higher in the list than any Release or shared symbol locations so it is searched first.
Select Save.

Confirm source file search paths If the debugger still does not step into the expected source files, ensure the source search paths are correct:

In Solution Explorer, select the solution and open Properties (Alt+Enter).
Go to Debug Source Files.
Under Directories containing source code, add the extension project’s source directory if it is not already listed.
Ensure only the intended source directories are listed and that no Release-only paths are masking the Debug sources.
Select OK or Apply.

Use the No Symbols Loaded page when hitting breakpoints If the debugger breaks into code and shows a No Symbols Loaded page for the extension module:

Use the options on that page to:
- Select New Path and add the Debug output folder for the extension, then select Load.
- Or select Browse and find <executable-name> and manually choose the correct .pdb in the Debug folder.
After the correct .pdb is found and loaded, the debugger will use the matching Debug symbols and source.

Ensure the project is actually building Debug for the experimental instance

Confirm the active configuration is Debug (not Release) in the toolbar when starting F5.
Rebuild the solution in Debug before starting the experimental instance.
If multiple configurations or output paths are defined in the project file, verify that the experimental instance is loading the DLL from the Debug output path (as seen in the Modules window). If it is loading from a Release path, adjust the project’s build output or VSIX packaging so the VSIX used by the experimental instance contains the Debug build.

Following these steps ensures that the experimental instance loads the Debug build of the extension and that the debugger resolves symbols and source from the Debug output, restoring full debugging capabilities.

References:

Answer 2

Adiba Khan 2,350 Microsoft External Staff

Thanks for reaching out. based on what you have described, the issue is that your VSIX extension is loading symbols from the Release output path instead of the Debug build, which prevents proper debugging in Visual Studio 2026.

For you module window, the .dll is loaded from installed extension location (program files) and symbols are loaded from release path (obj/Release/...). This indicates Visual Studio is running the installed VSIX, not the experimental instance with Debug build.

Resolution Steps

Ensure Debug configuration is active
1. Set the solution configuration to Debug
2. Rebuild the solution
Run Correct Startup Project(VSIX)
1. Right-click your VSIX project -> Set as Startup project
2. Press F5 This should launch the Experimental instance of Visual Studio, not the main installed one. if its not opening Experimental Instance:
3. Check .csproj
```
      <StartAction>Program</StartAction>
      <StartProgram>$(DevEnvDir)devenv.exe</StartProgram>
      <StartArguments>/rootsuffix Exp</StartArguments>
```
Remove installed VSIX (important) Currently your extension is being picked from installed location.
1. Go to:
```
      Extensions -> Manage Extensions -> Installed
```
2. Uninstall your extension
3. Restart Visual Studio
Verify VSIX manifest assets your manifest currently includes:
```
   Asset Type =" Microsoft.VisualStudio.VsPackage"
   
```
Ensure:
1. Output path is not hardcoded to Release
2. No prebuilt binaries are referenced

Disable "Optimize code" for debug in .csproj:

   <Optimize>false</Optimize>
   <DebugType>full</DebugType>

Clear experimental Instance Cache Run:
```
   devenv /rootsuffix Exp /resetuserdata
   
   
```
This ensures no stale extension cache is used.
Confirm Symbols Load from Debug Path After F5:
1. go to debug -> Windows -> Modules
2. Verify:
  1. Path -> bin\Debug..
  2. Symbols -> Loaded from debug .pdb

if the answer is the right solution, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment"

Adiba Khan 2,350 Reputation points Microsoft External Staff

2026-03-25T08:48:15.4933333+00:00

Hope you’re doing well. We’re following up on this thread to check if the issue is still occurring or has been resolved. If it has been resolved, kindly mark the answer as accepted. We will proceed with thread closure by 26 march

Looking forward to your response.

Best Regards.
Devesh Ketan Patel 0 Reputation points

2026-03-26T07:08:18.5666667+00:00

The name of the Extension that I am trying to debug is the TWVSSCM Extension. As you can see in the image, I have started the experimental instance but I cannot see TWVSSCM in the Modules Pane after uninstalling the Extension
Adiba Khan 2,350 Reputation points Microsoft External Staff

2026-03-27T11:10:03.8733333+00:00
Thanks for the update, this clarifies the situation. it means the extension is not being loaded at all, which is why debugging cannot attach.

Recommended Fix

Verify VSIX is actually deployed to Experimental instance When you press F5, Visual Studio should:

build the VSIX

Deploy it to the Exp instance

Launch devenv.exe /rootsuffix Exp Check output Window:
View -> Output -> Show output from: Debug
Look for:
Installing extension to Experimental Instance...
if you don't see this, deployment is failing.

Ensure VSIX project is Startup Project This is critical:

Right-click VSIX project -> Set as Startup Project

Not the class library project

Confirm .csproj has correct VSIX settings Your VSIX project should include:
<PropertyGroup> <IncludeAssemblyInVSIXContainer>true</IncludeAssemblyInVSIXContainer> <IncludeDebugSymbolsInVSIXContainer>true</IncludeDebugSymbolsInVSIXContainer> </ProjectGroup>
Without this, the DLL won't be packaged -> module won't load.

Check ActivityLog in Experimental Instance Launch Experimental instance and run:
devenv /rootsuffix Exp /log
then open:
%APPDATA%\Microsoft\VisualStudio\17.0_Exp\ActivityLog.xml
Look for:

Extension load failures

MEF composition errors

Missing assemblies

Ensure Extension is Triggered Even if deployed, VSIX loads only when needed. if your extension:

Adds menu -> click the menu

Adds tool windows -> open it.

Uses command -> execute it

otherwise it will not appear in modules.

Force Load via AutoLoad (for debugging) Temporarily add:
[ProvideAutoLoad(UIContextGuide80.NoSolution, PackageAutoLoadFlags.BackgroundLoad)]
This ensures the package loads immediately -> will appear in Modules.

Clean Experimental Instance completely Run:
devenv /rootsuffix Exp /resetuserdata
Then:

Rebuild

Press F5 again.

if the answer is the right solution, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment"
Adiba Khan 2,350 Reputation points Microsoft External Staff

2026-03-31T06:16:43.74+00:00

Hope you’re doing well. We’re following up on this thread to check if the issue is still occurring or has been resolved. If it has been resolved, kindly mark the answer as accepted. We will proceed with thread closure by 2nd april

Looking forward to your response.

Best Regards.
Devesh Ketan Patel 0 Reputation points

2026-03-31T11:55:45.04+00:00
ActivityLog.xml Installing_Log_Not_Found.png

Hello,

I am not able to see 'Installing extension to Experimental Instance' in my Debug Output Pane. I have attached the screenshot of the same.

I have ensured that my VSIX Project is the Startup Project.

I have also confirmed that the two properties you have mentioned in .csproj are set to true.

I have attached the ActivityLog.xml that I got after starting the Experimental Instance using the command devenv /rootsuffix Exp /log and then attaching my extension TWVSSCM to that process.

I have tried to open tool windows related to the extension, but it is still picking the released extension, not the one I am debugging.

I have tried force load via AutoLoad and I am still not able to debug the Extension.

I have tried cleaning the Experimental Instance also.

Apart from this, I am attaching the .csproj, .vsixmanifest and Extensionpackage.cs file againTWVSSCMPackage.cs.txt source.extension.vsixmanifest.txt TWVSSCM.csproj.txt
Adiba Khan 2,350 Reputation points Microsoft External Staff

2026-04-01T11:06:21.4233333+00:00
Thank you for detailed follow-up and for sharing all the artifacts. Based on everything you've confirmed, the key symptom now is:

No "Installing extension to Experimental instance" in Output

Extension DLL not coming from Debug path

Still seeing binaries from Program Files (installed files)

Final Root Cause

This behavior strongly indicates that: Your VSIX project is NOT being used during F5 debugging.

Even though it is set as StartUp Project, Visual Studio is launching without VSIX deployment step, which typically happens when:

The Project is NOT recognized as a VSIX debugging project

Recommended Fix:

Verify Project Type (Critical) Open your .csproj and confirm it uses VS SDK style:
<Project Sdk="Microsoft.NET.Sdk" <ProjectGroup> <TargetFramework>net472</TargetFramework> </ProjectGroup> <ItemGroup> <PackageReference Include="Microsoft.VisualStudio.SDK" Version="17.0.0" PrivateAssets="aall"/> </ItemGroup>
if this is missing or incorrect -> VSIX deployment will NOT trigger

Ensure VSIX Container Project Exists From your screenshots, it looks like:

TWSSCM = main logic project

But you may be missing a proper VSIX packaging project You must have a separate project of type: VSIX Project (.vsix) This project should:

Contain source.extension.vsixmanifest

Reference your main extension project

Fix Manifest Project Reference In source.extension.vsixmanifest:
<Asset Type ="Microsoft.VisualStudio.VsPackage" d:Source="Project" d:ProjectName="TWVSSCM" Path="|TWVSSCM;PkgdefProjectOutputGroup|"/>
Ensure:

ProjectName exactly matches your project

PkgdefProjectOutputGroup is used (important for packages)

Check Debug profile Go to:
Project Properties -> Debug
Ensure:

Start External program:
C:\Program Files\Microsoft Visual Studio\2026\...\devenv.exe

Arguments:
/rootsuffix Exp

Recreate Experimental Instance(Clean Reset) Run:
devenv /rootsuffix Exp /resetuserdata
Then delete manually if needed:
%LocalAPPData%\Microsoft\VisualStudio\17.0_Exp

Validate VSIX Build Option After build, check:
bin\Debug\*.vsix
if .vsix is not generated -> packaging is broken

Important observation from screenshot Modules show: path as microsoft visual studio, this confirms: You are debugging the installed extension, not local build.

Quick Fix:

Create a new VSIX Project in Visual Studio 2026

Add reference to your TWVSSCM project

Move your .vsixmanifest there

Set the new VSIX project as Startup

Press F5

This guarantees proper deployment+debugging

Expected result after fix

Output shows:

Installing extension to Experimental Instance...

Modules window shows:

TWVSSCM.dll -> bin\Debug\ Symbols loaded

At this point, this is not a symbol/debugging issue anymore-it is purely a VSIX packaging & deployment pipeline issue.

if the answer is the right solution, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Adiba Khan 2,350 Reputation points Microsoft External Staff

2026-04-07T10:16:02.2+00:00

We haven’t received any further updates or follow-up on this case, so we’ll proceed with closing it at this time. If you require additional assistance or have new information to share, please feel free to raise new thread, we’re happy to support you further needed.
Gabriel B 1 Reputation point

2026-07-13T16:54:05.85+00:00
@Devesh Ketan Patel

What made it finally work for me was to check a checkbox in the VSIX settings called "Deploy VSIX content to experimental instance for debugging". This adds the node

<DeployExtension>True</DeployExtension>

to your csproj (only for the Debug configuration).