Cannot debug wasm based blazor webapp projects after new release

[NikPiermafrost]

Type: Bug

Issue Description

Updated to C# 2.140.8. Before the update, i can press f5 and debug my application with chromium opening no issue to have wasm based breakpoints. Now the dev server does not start and remains pending, unable to debug my application

Steps to Reproduce

• Update to 2.140.8
• press f5 to launch a blazor webapp interactive client application
• Chromium / Chrome page doesn't launch

Expected Behavior

• press f5 to launch a blazor webapp interactive client application
• Chromium / Chrome page launches with debugger atached

Actual Behavior

• Chromium / Chrome page doesn't launch and debugger is stuck

Extension version: 2.140.8
VS Code version: Code 1.120.0 (0958016b2af9f09bb4257e0df4a95e2f90590f9f, 2026-05-12T20:17:22Z)
OS version: Linux x64 7.0.0-15-generic
Modes:

Logs

C# log

Details

2026-05-15 10:51:34.124 [info] Locating .NET runtime version 10.0.5
2026-05-15 10:51:34.406 [info] Dotnet path: /home/nick/.dotnet/dotnet
2026-05-15 10:51:34.406 [info] Activating C# + C# Dev Kit...
2026-05-15 10:51:34.627 [info] info: Program[0]
2026-05-15 10:51:34.627 [info]       Server started with process ID 1421130
2026-05-15 10:51:35.085 [info] [Program] Language server initialized
2026-05-15 10:51:35.088 [info] [Program] Monitoring client process 1419972 for exit
2026-05-15 10:51:35.537 [info] [initialized] [Microsoft.CodeAnalysis.LanguageServer.FileBasedPrograms.FileBasedProgramsEntryPointDiscovery] Finished discovery in '/home/nick/repos/work/[REDACTED]' in 11 milliseconds

C# LSP Trace Logs log

Details

Environment Information

VSCode version: 1.120.0
C# Extension: 2.140.8
Using OmniSharp: false

Dotnet Information

.NET SDK: Version: 10.0.300 Commit: caa81fa497 Workload version: 10.0.300-manifests.b47d7e23 MSBuild version: 18.6.3+caa81fa49

Runtime Environment:
OS Name: ubuntu
OS Version: 26.04
OS Platform: Linux
RID: linux-x64
Base Path: /home/nick/.dotnet/sdk/10.0.300/

.NET workloads installed:
There are no installed workloads to display.
Configured to use workload sets when installing new manifests.
No workload sets are installed. Run "dotnet workload restore" to install a workload set.

Host:
Version: 10.0.8
Architecture: x64
Commit: 94ea82652c

.NET SDKs installed:
8.0.420 [/home/nick/.dotnet/sdk]
10.0.203 [/home/nick/.dotnet/sdk]
10.0.300 [/home/nick/.dotnet/sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 8.0.26 [/home/nick/.dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 10.0.7 [/home/nick/.dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 10.0.8 [/home/nick/.dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 8.0.26 [/home/nick/.dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 10.0.7 [/home/nick/.dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 10.0.8 [/home/nick/.dotnet/shared/Microsoft.NETCore.App]

Other architectures found:
None

Environment variables:
DOTNET_CLI_TELEMETRY_OPTOUT [1]
DOTNET_CLI_UI_LANGUAGE [en-US]
DOTNET_ROOT [/home/nick/.dotnet]
DOTNET_WATCH_PROCESS_CLEANUP_TIMEOUT_MS [100]

global.json file:
Not found

Learn more:
https://aka.ms/dotnet/info

Download .NET:
https://aka.ms/dotnet/download

Visual Studio Code Extensions

Extension	Author	Version	Folder Name
astro-vscode	astro-build	2.16.14	astro-build.astro-vscode-2.16.14-linux-x64
autoimport	steoates	1.5.4	steoates.autoimport-1.5.4
blazorwasm-companion	ms-dotnettools	1.1.4	ms-dotnettools.blazorwasm-companion-1.1.4
cmake-tools	ms-vscode	1.23.52	ms-vscode.cmake-tools-1.23.52
comment-anchors	ExodiusStudios	1.10.4	exodiusstudios.comment-anchors-1.10.4
cpp-devtools	ms-vscode	0.5.13	ms-vscode.cpp-devtools-0.5.13
cpptools	ms-vscode	1.32.2	ms-vscode.cpptools-1.32.2-linux-x64
cpptools-extension-pack	ms-vscode	1.5.1	ms-vscode.cpptools-extension-pack-1.5.1
cpptools-themes	ms-vscode	2.0.0	ms-vscode.cpptools-themes-2.0.0
csdevkit	ms-dotnettools	3.20.195	ms-dotnettools.csdevkit-3.20.195-linux-x64
csharp	ms-dotnettools	2.140.8	ms-dotnettools.csharp-2.140.8-linux-x64
erb	CraigMaslowski	0.0.1	craigmaslowski.erb-0.0.1
FreeMarker	dcortes92	0.0.9	dcortes92.freemarker-0.0.9
gruvbox	jdinhlife	1.29.1	jdinhlife.gruvbox-1.29.1
markdown-all-in-one	yzhang	3.6.3	yzhang.markdown-all-in-one-3.6.3
material-icon-theme	PKief	5.34.0	pkief.material-icon-theme-5.34.0
ng-template	Angular	21.2.3	angular.ng-template-21.2.3
npm-intellisense	christian-kohler	1.4.5	christian-kohler.npm-intellisense-1.4.5
playwright	ms-playwright	1.1.19	ms-playwright.playwright-1.1.19
postcss	csstools	1.0.9	csstools.postcss-1.0.9
remote-containers	ms-vscode-remote	0.459.0	ms-vscode-remote.remote-containers-0.459.0
remote-explorer	ms-vscode	0.5.0	ms-vscode.remote-explorer-0.5.0
remote-server	ms-vscode	1.5.3	ms-vscode.remote-server-1.5.3
remote-ssh	ms-vscode-remote	0.122.0	ms-vscode-remote.remote-ssh-0.122.0
remote-ssh-edit	ms-vscode-remote	0.87.0	ms-vscode-remote.remote-ssh-edit-0.87.0
remote-wsl	ms-vscode-remote	0.104.3	ms-vscode-remote.remote-wsl-0.104.3
ruby-extensions-pack	Shopify	0.1.14	shopify.ruby-extensions-pack-0.1.14
ruby-lsp	Shopify	0.10.3	shopify.ruby-lsp-0.10.3
ruby-rubocop	misogi	0.8.6	misogi.ruby-rubocop-0.8.6
svelte-vscode	svelte	110.0.0	svelte.svelte-vscode-110.0.0
uncanny-cognitive-complexity	Dabolus	1.2.0	dabolus.uncanny-cognitive-complexity-1.2.0
vscode-azure-github-copilot	ms-azuretools	1.0.201	ms-azuretools.vscode-azure-github-copilot-1.0.201-linux-x64
vscode-azure-mcp-server	ms-azuretools	2.0.43	ms-azuretools.vscode-azure-mcp-server-2.0.43-linux-x64
vscode-azurefunctions	ms-azuretools	1.21.0	ms-azuretools.vscode-azurefunctions-1.21.0
vscode-azureresourcegroups	ms-azuretools	0.12.4	ms-azuretools.vscode-azureresourcegroups-0.12.4
vscode-azurestaticwebapps	ms-azuretools	0.13.2	ms-azuretools.vscode-azurestaticwebapps-0.13.2
vscode-azurestorage	ms-azuretools	0.17.1	ms-azuretools.vscode-azurestorage-0.17.1
vscode-commons	redhat	0.0.6	redhat.vscode-commons-0.0.6
vscode-containers	ms-azuretools	2.4.4	ms-azuretools.vscode-containers-2.4.4
vscode-dotnet-runtime	ms-dotnettools	3.0.2	ms-dotnettools.vscode-dotnet-runtime-3.0.2
vscode-eslint	dbaeumer	3.0.24	dbaeumer.vscode-eslint-3.0.24
vscode-kubernetes-tools	ms-kubernetes-tools	1.3.29	ms-kubernetes-tools.vscode-kubernetes-tools-1.3.29
vscode-node-azure-pack	ms-vscode	1.8.2	ms-vscode.vscode-node-azure-pack-1.8.2
vscode-rdbg	KoichiSasada	0.2.2	koichisasada.vscode-rdbg-0.2.2
vscode-remote-extensionpack	ms-vscode-remote	0.26.0	ms-vscode-remote.vscode-remote-extensionpack-0.26.0
vscode-tailwindcss	bradlc	0.14.29	bradlc.vscode-tailwindcss-0.14.29
vscode-xml	redhat	0.29.2	redhat.vscode-xml-0.29.2-linux-x64
vscode-yaml	redhat	1.23.0	redhat.vscode-yaml-1.23.0

C# Settings

Setting	Value
preferCSharpExtension	false
compilerDiagnosticScope	openFiles
analyzerDiagnosticScope	openFiles
enableXamlTools	true
useServerGC	true

System Info

Item	Value
CPUs	Intel(R) Core(TM) Ultra 7 155H (22 x 4129)
GPU Status	2d_canvas: enabled GPU0: VENDOR= 0x8086 [Google Inc. (Intel)], DEVICE=0x7d55 [ANGLE (Intel, Mesa Intel(R) Arc(tm) Graphics (MTL), OpenGL ES 3.2 Mesa 26.0.3-1ubuntu1)], DRIVER_VENDOR=Mesa, DRIVER_VERSION=26.0.3 ACTIVE Machine model name: Machine model version: direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled multiple_raster_threads: enabled_on opengl: enabled_on rasterization: enabled raw_draw: disabled_off_ok skia_graphite: disabled_off trees_in_viz: disabled_off video_decode: enabled video_encode: disabled_software vulkan: disabled_off webgl: enabled webgl2: enabled webgpu: disabled_off webnn: disabled_off
Load (avg)	2, 2, 2
Memory (System)	30.31GB (4.86GB free)
Process Argv
Screen Reader	no
VM	67%
DESKTOP_SESSION	ubuntu
XDG_CURRENT_DESKTOP	ubuntu:GNOME
XDG_SESSION_DESKTOP	ubuntu
XDG_SESSION_TYPE	wayland

[gregg-miskelly]

Thanks for reporting this!

Can someone supply a "Protocol Messages" log: https://github.com/dotnet/vscode-csharp/blob/main/docs/debugger/Enabling-C%23-debugger-logging.md

[thaystg]

Hello!
If you disable the new wasm debugger it works for you?

Thanks

[gregg-miskelly]

It turns out that we have a debugger regression in 2.140.8, that might be what you are running into. So, if you are still seeing this problem after unchecking that option, can you check this: #9311 (comment)

[NikPiermafrost]

@thaystg it seems to at least launch the server and debug the was disabling the new wasm debugger as expected. Enabling back the feature makes the bug come back. @gregg-miskelly differently from that thread i do not have razor runtime compilation

[thaystg]

Can you please test with this version 2.142.16?

[NikPiermafrost]

@thaystg still stuck

[thaystg]

Can you please share with us the test app that you are using?
And how are your config files to use chromium/chrome?
Are you using c# dev kit or do you have a launch.json file? How is it?

[NikPiermafrost]

@thaystg
I recreated the same issue with a new blazor webapp with the following command to avoid any existing project configuration conflicts:
dotnet new blazor --interactivity Auto --no-https --name TestForRegression
The i pressed f5 and selected the server project (since it's interactive auto)
With the settings, it doesn't launch.
Without it, it does launch
i do not have any particular chromium config. I just ran "sudo apt install chromium" (which installs the snap version of chromium)
I do not have any launch.json file in any project. I press f5, select the project and go.
I must tell you that ataching to a process makes the debugger work on the server project, not the client