Auto completion not working on file-based apps?

[cvertee]

Type: Bug

Issue Description

Steps to Reproduce

• Create %anyname%.cs anywhere, open this file (not directory) with vscode.
• Try typing something like Console.WriteLine
• See that autocompletion isn't working

Expected Behavior

Autocompletion is working, intellisense helps with code and other stuff

Actual Behavior

Just nothing. It can only see variables/etc but for stuff like var sw = new StreamWriter(listGeneralPath, true) when i type sw. nothing is shown

Extension version: 2.100.11
VS Code version: Code 1.106.1 (cb1933bbc38d329b3595673a600fab5c7368f0a7, 2025-11-16T10:20:23.745Z)
OS version: Windows_NT x64 10.0.19045
Modes:

Logs

C# log

2025-11-18 22:30:23.406 [info] Installing C# dependencies...
2025-11-18 22:30:23.406 [info] 

2025-11-18 22:30:23.406 [info] Platform: win32, x86_64

2025-11-18 22:30:23.406 [info] 

2025-11-18 22:30:23.406 [info] Downloading package 'Language server for Roslyn Copilot integration' 
2025-11-18 22:30:24.558 [info] (47 KB)
2025-11-18 22:30:24.558 [info] .......
2025-11-18 22:30:24.765 [info] .......
2025-11-18 22:30:24.766 [info] ......
2025-11-18 22:30:24.766 [info]  Done!

2025-11-18 22:30:24.767 [info] Validating download...

2025-11-18 22:30:24.767 [info] Integrity Check succeeded.

2025-11-18 22:30:24.767 [info] Installing package 'Language server for Roslyn Copilot integration'

2025-11-18 22:30:24.767 [info] 

2025-11-18 22:30:24.774 [info] Finished

2025-11-18 22:30:24.774 [info] 

2025-11-18 22:30:25.333 [info] Locating .NET runtime version 9.0.1
2025-11-18 22:30:25.419 [info] Dotnet path: C:\Program Files\dotnet\dotnet.exe
2025-11-18 22:30:25.419 [info] Activating C# + C# Dev Kit...
2025-11-18 22:30:25.560 [info] [stdout] info: Program[0]
      Server started with process ID 10080

2025-11-18 22:30:26.463 [info] [stdout] {"pipeName":"\\\\.\\pipe\\66fabd66"}

2025-11-18 22:30:26.463 [info] received named pipe information from server
2025-11-18 22:30:26.463 [info] client has connected to server
2025-11-18 22:30:26.557 [info] [Program] Language server initialized
2025-11-18 22:32:18.650 [info] Locating .NET runtime version 9.0.1
2025-11-18 22:32:18.733 [info] Dotnet path: C:\Program Files\dotnet\dotnet.exe
2025-11-18 22:32:18.733 [info] Activating C# + C# Dev Kit...
2025-11-18 22:32:18.859 [info] [stdout] info: Program[0]
      Server started with process ID 13896

2025-11-18 22:32:19.328 [info] [stdout] {"pipeName":"\\\\.\\pipe\\9b3bd6f9"}

2025-11-18 22:32:19.328 [info] received named pipe information from server
2025-11-18 22:32:19.329 [info] client has connected to server
2025-11-18 22:32:19.438 [info] [Program] Language server initialized
2025-11-18 22:34:51.540 [info] Locating .NET runtime version 9.0.1
2025-11-18 22:34:51.576 [info] Dotnet path: C:\Program Files\dotnet\dotnet.exe
2025-11-18 22:34:51.576 [info] Activating C# standalone...
2025-11-18 22:34:51.751 [info] [stdout] info: Program[0]
      Server started with process ID 12388

2025-11-18 22:34:52.444 [info] [stdout] {"pipeName":"\\\\.\\pipe\\b6e2a0da"}

2025-11-18 22:34:52.444 [info] received named pipe information from server
2025-11-18 22:34:52.445 [info] client has connected to server
2025-11-18 22:34:52.538 [info] [Program] Language server initialized
2025-11-18 22:35:24.645 [info] Detected new installation of ms-dotnettools.csdevkit
2025-11-18 22:35:28.151 [info] Locating .NET runtime version 9.0.1
2025-11-18 22:35:28.272 [info] Dotnet path: C:\Program Files\dotnet\dotnet.exe
2025-11-18 22:35:28.273 [info] Activating C# + C# Dev Kit...
2025-11-18 22:35:28.401 [info] [stdout] info: Program[0]
      Server started with process ID 3692

2025-11-18 22:35:28.879 [info] [stdout] {"pipeName":"\\\\.\\pipe\\8525f145"}

2025-11-18 22:35:28.879 [info] received named pipe information from server
2025-11-18 22:35:28.880 [info] client has connected to server
2025-11-18 22:35:28.980 [info] [Program] Language server initialized
2025-11-18 22:37:26.701 [info] Locating .NET runtime version 9.0.1
2025-11-18 22:37:26.784 [info] Dotnet path: C:\Program Files\dotnet\dotnet.exe
2025-11-18 22:37:26.784 [info] Activating C# + C# Dev Kit...
2025-11-18 22:37:26.921 [info] [stdout] info: Program[0]
      Server started with process ID 15592

2025-11-18 22:37:27.438 [info] [stdout] {"pipeName":"\\\\.\\pipe\\5004b59e"}

2025-11-18 22:37:27.438 [info] received named pipe information from server
2025-11-18 22:37:27.438 [info] client has connected to server
2025-11-18 22:37:27.538 [info] [Program] Language server initialized

C# LSP Trace Logs log

Environment Information

VSCode version: 1.106.1
C# Extension: 2.100.11
Using OmniSharp: false

Dotnet Information

.NET SDK: Version: 10.0.100 Commit: b0f34d51fc Workload version: 10.0.100-manifests.4c0ca8ba MSBuild version: 18.0.2+b0f34d51f

Runtime Environment:
OS Name: Windows
OS Version: 10.0.19045
OS Platform: Windows
RID: win-x64
Base Path: C:\Program Files\dotnet\sdk\10.0.100\

.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: 10.0.0
Architecture: x64
Commit: b0f34d51fc

.NET SDKs installed:
10.0.100 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 10.0.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 7.0.20 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 10.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 7.0.20 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 10.0.0 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Other architectures found:
None

Environment variables:
DOTNET_CLI_UI_LANGUAGE [en-US]
DOTNET_MULTILEVEL_LOOKUP [undefined]

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
cpptools	ms-vscode	1.28.3	ms-vscode.cpptools-1.28.3-win32-x64
csdevkit	ms-dotnettools	1.80.7	ms-dotnettools.csdevkit-1.80.7-win32-x64
csharp	ms-dotnettools	2.100.11	ms-dotnettools.csharp-2.100.11-win32-x64
debugpy	ms-python	2025.16.0	ms-python.debugpy-2025.16.0-win32-x64
go	golang	0.50.0	golang.go-0.50.0
jupyter	ms-toolsai	2025.9.1	ms-toolsai.jupyter-2025.9.1-win32-x64
jupyter-keymap	ms-toolsai	1.1.2	ms-toolsai.jupyter-keymap-1.1.2
jupyter-renderers	ms-toolsai	1.3.0	ms-toolsai.jupyter-renderers-1.3.0
python	ms-python	2025.18.0	ms-python.python-2025.18.0-win32-x64
rust-analyzer	rust-lang	0.3.2683	rust-lang.rust-analyzer-0.3.2683-win32-x64
vscode-dotnet-runtime	ms-dotnettools	2.3.7	ms-dotnettools.vscode-dotnet-runtime-2.3.7
vscode-jupyter-cell-tags	ms-toolsai	0.1.9	ms-toolsai.vscode-jupyter-cell-tags-0.1.9
vscode-jupyter-slideshow	ms-toolsai	0.1.6	ms-toolsai.vscode-jupyter-slideshow-0.1.6
vscode-pylance	ms-python	2025.9.1	ms-python.vscode-pylance-2025.9.1
vscode-python-envs	ms-python	1.12.0	ms-python.vscode-python-envs-1.12.0-win32-x64

C# Settings

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

System Info

Item	Value
CPUs	AMD Ryzen 5 3600 6-Core Processor (12 x 3593)
GPU Status	2d_canvas: enabled 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: enabled vulkan: disabled_off webgl: enabled webgl2: enabled webgpu: enabled webnn: disabled_off
Load (avg)	undefined
Memory (System)	31.95GB (24.27GB free)
Process Argv	--crash-reporter-id 10b94d38-98e4-4a90-962a-a9fe1d02647e
Screen Reader	no
VM	0%

A/B Experiments

vsliv368:30146709
binariesv615:30325510
nativeloc1:31344060
dwcopilot:31170013
dwoutputs:31242946
copilot_t_ci:31333650
e5gg6876:31282496
pythonrdcb7:31342333
aj953862:31281341
nes-set-on:31351930
6abeh943:31336334
editstats-enabled:31346257
aa_t:31379598
t123456:31413567
gaj49834:31404438
cloudbuttont:31379625
todos-1:31405332
v66_all_req:31402695
treatment_gpt5applypatchexclusively:31412086
3efgi100_wstrepl:31403338
trigger-command-fix:31379601
auto_model_enabled:31385282
use-responses-api:31390855
afag3459:31419926
673df989:31418077
ff8f5884:31411053
defaultvisibility:31420717
c0683394:31419495

[cvertee]

Also it seems that it works for several seconds like a normal idk syntax highlighter but after that time every syntax highlighting is gone

Before trustign workspace and reloading extensions and waiting for 1-2 seconds

After

[dibarbet]

@cvertee can you check if the dotnet.projects.enableFileBasedPrograms is enabled? If not you'll need to turn it on to add support for file based programs.

[cvertee]

@dibarbet nah doesn't help. Also had weird error when i opened file-based cs file

Error output of C# extension (i guess)

2025-11-19 21:56:50.863 [info] Locating .NET runtime version 9.0.1
2025-11-19 21:56:50.958 [info] Dotnet path: C:\Program Files\dotnet\dotnet.exe
2025-11-19 21:56:50.958 [info] Activating C# + C# Dev Kit...
2025-11-19 21:56:51.261 [info] [stdout] info: Program[0]
      Server started with process ID 11000

2025-11-19 21:56:51.906 [info] [stdout] {"pipeName":"\\\\.\\pipe\\0c8d8b71"}

2025-11-19 21:56:51.906 [info] received named pipe information from server
2025-11-19 21:56:51.907 [info] client has connected to server
2025-11-19 21:56:52.017 [info] [Program] Language server initialized
2025-11-19 21:57:22.306 [info] Locating .NET runtime version 9.0.1
2025-11-19 21:57:22.385 [info] Dotnet path: C:\Program Files\dotnet\dotnet.exe
2025-11-19 21:57:22.385 [info] Activating C# + C# Dev Kit...
2025-11-19 21:57:22.511 [info] [stdout] info: Program[0]
      Server started with process ID 17828

2025-11-19 21:57:22.985 [info] [stdout] {"pipeName":"\\\\.\\pipe\\97b466f6"}

2025-11-19 21:57:22.985 [info] received named pipe information from server
2025-11-19 21:57:22.985 [info] client has connected to server
2025-11-19 21:57:23.087 [info] [Program] Language server initialized
2025-11-19 21:57:23.903 [info] [textDocument/_vs_getProjectContexts] [Microsoft.CodeAnalysis.LanguageServer.DotnetCliHelper] Using dotnet executable configured on the PATH
2025-11-19 21:57:24.499 [info] [textDocument/_vs_getProjectContexts] [Microsoft.CodeAnalysis.MSBuild.BuildHostProcessManager] .NET BuildHost started from c:\Users\cver\.vscode\extensions\ms-dotnettools.csharp-2.100.11-win32-x64\.roslyn\Microsoft.CodeAnalysis.LanguageServer.exe reloading to start from C:\Program Files\dotnet\dotnet.exe to match necessary SDK location.
2025-11-19 21:57:53.152 [error] [textDocument/_vs_getProjectContexts] [LanguageServerProjectLoader] Error while loading e:\test.cs: Возникло исключение: "System.UriFormatException: Failed create URI from 'e:'; original string: 'e:'
 ---> System.UriFormatException: Invalid URI: The format of the URI could not be determined.
   at System.Uri.CreateThis(String uri, Boolean dontEscape, UriKind uriKind, UriCreationOptions& creationOptions)
   at System.Uri..ctor(String uriString, UriKind uriKind)
   at Microsoft.CodeAnalysis.LanguageServer.ProtocolConversions.CreateAbsoluteUri(String absolutePath) in /_/src/LanguageServer/Protocol/Extensions/ProtocolConversions.cs:line 205
   --- End of inner exception stack trace ---
   at Microsoft.CodeAnalysis.LanguageServer.ProtocolConversions.CreateAbsoluteUri(String absolutePath) in /_/src/LanguageServer/Protocol/Extensions/ProtocolConversions.cs:line 213
   at Microsoft.CodeAnalysis.LanguageServer.ProtocolConversions.CreateRelativePatternBaseUri(String path) in /_/src/LanguageServer/Protocol/Extensions/ProtocolConversions.cs:line 243
   at Microsoft.CodeAnalysis.LanguageServer.HostWorkspace.FileWatching.LspFileChangeWatcher.FileChangeContext.<>c.<.ctor>b__7_0(WatchedDirectory d) in /_/src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/HostWorkspace/FileWatching/LspFileChangeWatcher.cs:line 88
   at System.Linq.Enumerable.ArraySelectIterator`2.Fill(ReadOnlySpan`1 source, Span`1 destination, Func`2 func)
   at System.Linq.Enumerable.ArraySelectIterator`2.ToArray()
   at Microsoft.CodeAnalysis.LanguageServer.HostWorkspace.FileWatching.LspFileChangeWatcher.FileChangeContext..ctor(ImmutableArray`1 watchedDirectories, LspFileChangeWatcher lspFileChangeWatcher) in /_/src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/HostWorkspace/FileWatching/LspFileChangeWatcher.cs:line 79
   at Microsoft.CodeAnalysis.LanguageServer.HostWorkspace.FileWatching.LspFileChangeWatcher.CreateContext(ImmutableArray`1 watchedDirectories) in /_/src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/HostWorkspace/FileWatching/LspFileChangeWatcher.cs:line 45
   at Microsoft.CodeAnalysis.LanguageServer.HostWorkspace.FileWatching.DelegatingFileChangeWatcher.CreateContext(ImmutableArray`1 watchedDirectories) in /_/src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/HostWorkspace/FileWatching/DelegatingFileChangeWatcher.cs:line 45
   at Microsoft.CodeAnalysis.Workspaces.ProjectSystem.ProjectSystemProject..ctor(ProjectSystemProjectFactory projectSystemProjectFactory, ProjectSystemHostInfo hostInfo, ProjectId id, String displayName, String language, String assemblyName, CompilationOptions compilationOptions, String filePath, ParseOptions parseOptions) in /_/src/Workspaces/Core/Portable/Workspace/ProjectSystem/ProjectSystemProject.cs:line 199
   at Microsoft.CodeAnalysis.Workspaces.ProjectSystem.ProjectSystemProjectFactory.CreateAndAddToWorkspaceAsync(String projectSystemName, String language, ProjectSystemProjectCreationInfo creationInfo, ProjectSystemHostInfo hostInfo) in /_/src/Workspaces/Core/Portable/Workspace/ProjectSystem/ProjectSystemProjectFactory.cs:line 106
   at Microsoft.CodeAnalysis.LanguageServer.HostWorkspace.LanguageServerProjectLoader.<>c__DisplayClass19_1.<<ReloadProjectAsync>g__GetOrCreateProjectTargetAsync|0>d.MoveNext() in /_/src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/HostWorkspace/LanguageServerProjectLoader.cs:line 374
--- End of stack trace from previous location ---
   at Microsoft.CodeAnalysis.LanguageServer.HostWorkspace.LanguageServerProjectLoader.ReloadProjectAsync(ProjectToLoad projectToLoad, ToastErrorReporter toastErrorReporter, BuildHostProcessManager buildHostProcessManager, CancellationToken cancellationToken) in /_/src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/HostWorkspace/LanguageServerProjectLoader.cs:line 284"

looks like there are some problems with path to file (I opened vscode directly to file not the directory) like E:/test.cs?

UPD: moved cs file to another directory, opened whole directory in vscode and now auto completion is working.