[Android 16] MonoVsDbg debugger fails on second F5 launch on physical device

[Hrishikesh46779]

Description

Description

The .NET MAUI Android debugger works on the first F5 launch, but after stopping debugging, the second and subsequent F5 launches fail to attach the MonoVsDbg debugger.

The issue is reproducible with a newly created .NET MAUI template project with no application-specific code or third-party NuGet packages.

The application can run using Ctrl+F5, but I need F5 because I require breakpoints.

Environment

• OS: Windows 11
• Visual Studio: Visual Studio Community 2026 18.9.1
• .NET SDK: 10.0.400
• Workload version: 10.0.400-manifests.b0ae88bd
• .NET MAUI: 10.0.80
• Android workload: 36.1.69/10.0.100
• iOS workload: 26.5.10301/10.0.100
• MAUI Windows workload: 10.0.20/10.0.100
• Target framework: net10.0-android
• Android version: Android 16 (API 36)
• Device: Physical Android device connected via USB
• CPU architecture: arm64-v8a
• Debugger: MonoVsDbg
• Hot Reload: Disabled

Important

I initially experienced this problem in my existing MAUI application.

To rule out application-specific code, I created a completely new MAUI template project and reproduced the same problem on the same physical Android 16 device.

Therefore, the issue can be reproduced with the default MAUI template.

Steps to Reproduce

1. Create a new .NET MAUI App using the Visual Studio 2026 template.
2. Target net10.0-android.
3. Connect an Android 16 physical device through USB.
4. Start debugging with F5.
5. The application launches successfully.
6. Stop debugging.
7. Start debugging again with F5.
8. The second debug session fails.
9. Repeat F5 again; subsequent attempts also fail.

Expected behavior

F5 → application starts → debugger attaches

After stopping:

F5 → application starts → debugger attaches again

This should continue working for every debug session.

Actual behavior

The first F5 works, but after stopping debugging, subsequent F5 attempts fail to establish the MonoVsDbg session.

Visual Studio reports:

The program 'MauiApp1.dll' has exited with code 0 (0x0).
Debug Address: 127.0.0.1
Debug Port: 8835
Debug Assets Directory: C:\Users\Hrishikesh\source\repos\MauiApp1\obj\Debug\net10.0-android\android\assets;C:\Users\Hrishikesh\source\repos\MauiApp1\obj\Debug\net10.0-android\android\assets\arm64-v8a
New MonoVsDbg debugger process created for project 'C:\Users\Hrishikesh\source\repos\MauiApp1\MauiApp1.csproj'...
New MonoVsDbg debugger process created for project 'C:\Users\Hrishikesh\source\repos\MauiApp1\MauiApp1.csproj'...
Starting MonoVsDbg debug session for project 'C:\Users\Hrishikesh\source\repos\MauiApp1\MauiApp1.csproj'...

am start -a "android.intent.action.MAIN" -c "android.intent.category.LAUNCHER" -n "com.companyname.mauiapp1/crc64e632a077a20c694c.MainActivity"
Starting: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] cmp=com.companyname.mauiapp1/crc64e632a077a20c694c.MainActivity }

08-23 22:57:44.801 I/nyname.mauiapp1(24572): Thread[2,tid=27410,WaitingInMainSignalCatcherLoop,Thread*=0xb4000075856ac010,peer=0x22aa020,"Signal Catcher"]: reacting to signal 3
08-23 22:57:44.801 I/nyname.mauiapp1(24572):
08-23 22:57:44.854 I/nyname.mauiapp1(24572): Wrote stack traces to tombstoned

Link to public reproduction project repository

No response

Version with bug

10.0.20

Is this a regression from previous behavior?

Yes, this used to work in .NET MAUI

Last version that worked well

Unknown/Other

Affected platforms

Android

Affected platform versions

Android 16

Did you find any workaround?

No response

Relevant log output

The program 'MauiApp1.dll' has exited with code 0 (0x0).
Debug Address: 127.0.0.1
Debug Port: 8835
Debug Assets Directory: C:\Users\Hrishikesh\source\repos\MauiApp1\obj\Debug\net10.0-android\android\assets;C:\Users\Hrishikesh\source\repos\MauiApp1\obj\Debug\net10.0-android\android\assets\arm64-v8a
New MonoVsDbg debugger process created for project 'C:\Users\Hrishikesh\source\repos\MauiApp1\MauiApp1.csproj'...
New MonoVsDbg debugger process created for project 'C:\Users\Hrishikesh\source\repos\MauiApp1\MauiApp1.csproj'...
New MonoVsDbg debugger process created for project 'C:\Users\Hrishikesh\source\repos\MauiApp1\MauiApp1.csproj'...
Starting MonoVsDbg debug session for project 'C:\Users\Hrishikesh\source\repos\MauiApp1\MauiApp1.csproj'...

am start -a "android.intent.action.MAIN" -c "android.intent.category.LAUNCHER" -n "com.companyname.mauiapp1/crc64e632a077a20c694c.MainActivity"
Starting: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] cmp=com.companyname.mauiapp1/crc64e632a077a20c694c.MainActivity }

08-23 23:31:08.214 I/nyname.mauiapp1(30042): Thread[2,tid=4271,WaitingInMainSignalCatcherLoop,Thread*=0xb4000075856ac010,peer=0x266a020,"Signal Catcher"]: reacting to signal 3
08-23 23:31:08.214 I/nyname.mauiapp1(30042):
08-23 23:31:08.330 I/nyname.mauiapp1(30042): Wrote stack traces to tombstoned

[dartasen]

https://developercommunity.visualstudio.com/t/MonoVsDbg-created-4-times-on-incremental/11134891

[Hrishikesh46779]

I tested the suggested adb forward --remove-all workaround.

It works when I execute the command manually immediately before pressing F5. However, placing the same command in either PreBuildEvent or an MSBuild BeforeTargets="Build" target does not fix the issue.

This is reproducible with a completely new default .NET MAUI template project on my physical Android 16 device.

The manual command is:
C:\Program Files (x86)\Android\android-sdk\platform-tools>adb forward --remove-all

[stevenbgoldmine]

Not that it helps but I experience the same issue 😔 I work around the issue by manually running:

C:\Program Files (x86)\Android\android-sdk\platform-tools>adb forward --remove-all

In a Developer Coomand Prompt Window in VS every time after the first run.