Corrupted error messages

[evanIT19]

Type: Bug

Issue Description

When I make code changes to a .cshtml file, any minor text change, the linter flags errors on nearly every line. If I restart VS Code the error flags clear. For example, I added a

block and now text above the block and below are showing random red error squiggle lines.

Steps to Reproduce

The file contains HTML and Razor shorthdand. I add an HTML element and the error flags fill the page.

Expected Behavior

No error flags on valid code.

Actual Behavior

Error flags on valid code.

Extension version: 2.140.9
VS Code version: Code 1.136.2 (88e44fa0e00b08f7758b4f6d05632e4fd5e4df6f, 2026-09-04T21:40:42Z)
OS version: Windows_NT x64 10.0.26200
Modes:

Logs

C# log

Details

2026-09-08 14:09:52.491 [info] Locating .NET runtime version 10.0.5
2026-09-08 14:09:53.844 [info] Dotnet path: C:\Program Files\dotnet\dotnet.exe
2026-09-08 14:09:53.844 [info] Activating C# + C# Dev Kit...
2026-09-08 14:09:54.559 [info] info: Program[0]
2026-09-08 14:09:54.559 [info]       Server started with process ID 34868
2026-09-08 14:09:55.289 [info] [Program] Language server initialized
2026-09-08 14:09:55.290 [info] [Program] Monitoring client process 30596 for exit
2026-09-08 14:09:55.707 [info] [initialized] [Microsoft.CodeAnalysis.LanguageServer.FileBasedPrograms.FileBasedProgramsEntryPointDiscovery] Finished discovery in 'c:\Users\e174835\Documents\customapps-repo\OpsLog.NET' in 7 milliseconds
2026-09-08 14:09:59.154 [info] [serviceBroker/connect] [WorkspaceProjectFactoryService] Project C:\Users\e174835\Documents\customapps-repo\OpsLog.NET\OpsLog.csproj loaded by C# Dev Kit
2026-09-08 14:11:01.889 [error] Request textDocument/formatting failed.
  Message: 'end' must not be less than 'start'. start='959' end='958'. (Parameter 'end')
  Code: -32000 
[object Object]

C# LSP Trace Logs log

Details

Environment Information

VSCode version: 1.136.2
C# Extension: 2.140.9
Using OmniSharp: false

Dotnet Information

.NET SDK: Version: 10.0.302 Commit: 35b593bebf Workload version: 10.0.300-manifests.714b12c0 MSBuild version: 18.6.11+35b593beb

Runtime Environment:
OS Name: Windows
OS Version: 10.0.26200
OS Platform: Windows
RID: win-x64
Base Path: C:\Program Files\dotnet\sdk\10.0.302\

.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: 10.0.10
Architecture: x64
Commit: f7d90799ce

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

.NET runtimes installed:
Microsoft.AspNetCore.App 8.0.26 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 10.0.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 10.0.10 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 6.0.36 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 8.0.26 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 9.0.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 10.0.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 10.0.10 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 6.0.36 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 8.0.26 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 9.0.5 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 10.0.6 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 10.0.10 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Other architectures found:
x86 [C:\Program Files (x86)\dotnet]
registered at [HKLM\SOFTWARE\dotnet\Setup\InstalledVersions\x86\InstallLocation]

Environment variables:
DOTNET_CLI_UI_LANGUAGE [en-US]
DOTNET_MULTILEVEL_LOOKUP [0]

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
csdevkit	ms-dotnettools	3.20.199	ms-dotnettools.csdevkit-3.20.199-win32-x64
csharp	ms-dotnettools	2.140.9	ms-dotnettools.csharp-2.140.9-win32-x64
powershell	ms-vscode	2025.4.0	ms-vscode.powershell-2025.4.0
vscode-dotnet-runtime	ms-dotnettools	3.1.0	ms-dotnettools.vscode-dotnet-runtime-3.1.0

C# Settings

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

System Info

Item	Value
CPUs	13th Gen Intel(R) Core(TM) i7-13700 (24 x 2112)
GPU Status	2d_canvas: enabled GPU0: VENDOR= 0x8086, DEVICE=0xa780 [Intel(R) UHD Graphics 770], DRIVER_VENDOR=Intel, DRIVER_VERSION=32.0.101.7077 ACTIVE GPU1: VENDOR= 0x1414, DEVICE=0x008c [Microsoft Basic Render Driver], DRIVER_VERSION=10.0.26100.8972 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: enabled webgl: enabled webgpu: enabled webnn: disabled_off
Load (avg)	undefined
Memory (System)	15.70GB (2.69GB free)
Process Argv	--crash-reporter-id 298a3818-57d5-4a4b-b81c-3ecd8a0533e3
Screen Reader	no
VM	0%

A/B Experiments

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cp_cls_t_966_ss:31526232
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c3h7c220:31478652
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conptydll_true:31498968
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chat:31457767
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jbcp_cls_pctr_t:31531130
cp_intellij_t_nes:31548657
jf4hg949:31526829
ahp-both-windows:31556933
ihg5j128:31534457
7g2b5551:31542111
nes-ex-cf-euporie-03:31542868
enable_editor_pane_layout:31569726
allow-none:31555437
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session-archive:31558132
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mangle-name-treatment:31572634
intellij_nes_preview_t:31580086
39a5d156:31574986
2bfb8b39:31576696
permission_prompt_control:1332567
ccr_pr_nudge_control:1319470
vsc_wsm_t:1340632
jidc7660:1370295
auto_mode_control:1367906
h5e14506_copy:1348995
1g5a5742:1379227

[davidwengier]

Thanks for the report @evanIT19. It would be good to get some more logs if possible, so we can really see what is going on. We have some specific Razor formatting logs that will tell us everything we need to know, but they are opt-in. Instructions for enabling them are at the bottom of https://aka.ms/razor-formatting-issue

If you can turn that on, restart VS Code, then reproduce the problem, zip up the logs, and attach them here, that would be great. Thanks,

[evanIT19]

Thanks for the pointer @davidwengier. I turned on Razor logging. In the past few days, the error has not reappeared. It feels so random that I don't know what is triggering it.

Using "Developer: Reload Window" also helps. Maybe this isn't a Razor formatting problem?

If it happens again, I'll check for error logs.

[davidwengier]

I suggested formatting because that is the only thing in the C# logs section of the original report. It doesn't sound like formatting from your description though, I'll admit. There is also a Record option in the Collect Logs command that would be useful for non-formatting issues, but that still relies on the problem being reproducible.

The other thing to do, if it's hard to reproduce, is to turn the C# logging in VS Code up to Trace (open the Output Pane, switch to C#, click the cog icon next to the drop down), and then just manually copy and paste the logs from the Output window into this report if it happens again.