Error when installing extension using VSIX file

[hjrb]

Type: Bug

Behaviour

Error message:
(FATAL ERROR: v8::ToLocalChecked Empty MaybeLocal, 1)
(----- Native stack trace -----, 1)
(, 1)
( 1: 00007FF790B6C4BA llhttp_get_upgrade+53466, 1)
( 2: 00007FF790C430A2 node::OnFatalError+290, 1)
( 3: 00007FF795D4BB2C v8::Function::NewInstance+1004, 1)
( 4: 00007FF795D4C064 v8::api_internal::ToLocalEmpty+20, 1)
( 5: 00007FF790CB7DAA uv_loop_fork+440954, 1)
( 6: 00007FF790CBA961 uv_loop_fork+452145, 1)
( 7: 00007FF794885670 v8::internal::compiler::CompilationDependencies::FieldTypeDependencyOffTheRecord+2339696, 1)
( 8: 00007FF7E01158D8 , 1)
(, 1)
(----- JavaScript stack trace -----, 1)
(, 1)
(1: getPackageScopeConfig (node:internal/modules/package_json_reader:160:33), 1)
(2: getPackageJSONURL (node:internal/modules/package_json_reader:237:25), 1)
(3: packageResolve (node:internal/modules/esm/resolve:778:81), 1)
(4: moduleResolve (node:internal/modules/esm/resolve:864:18), 1)
(5: defaultResolve (node:internal/modules/esm/resolve:994:11), 1)
(6: nextResolve (node:internal/modules/esm/hooks:748:28), 1)
(7: resolve (data:text/javascript;base64,CglleHBvcnQgYXN5bmMgZnVuY3Rpb24gcmVzb2x2ZShzcGVjaWZpZXIsIGNvbnRleHQsIG5leHRSZXNvbHZlKSB7CgkJaWYgKHNwZWNpZmllciA9PT0gJ2ZzJykgewoJCQlyZXR1cm4gewoJCQkJZm9ybWF0OiAnYnVpbHRpbicsCgkJCQlzaG9ydENpcmN1aXQ6IHRydWUsCgkJCQl1cmw6ICdub2RlOm9yaWdpbmFsLWZzJwoJCQl9OwoJCX0KCgkJLy8gRGVmZXIgdG8gdGhlIG5leHQgaG9vayBpbiB0aGUgY2hhaW4sIHdoaWNoIHdvdWxkIGJlIHRoZQoJCS8vIE5vZGUuanMgZGVmYXVsdCByZXNvbHZlIGlmIHRoaXMgaXMgdGhlIGxhc3QgdXNlci1zcGVjaWZpZWQgbG9hZGVyLgoJCXJldHVybiBuZXh0UmVzb2x2ZShzcGVjaWZpZXIsIGNvbnRleHQpOwoJfQ==:13:10), 1)
(8: nextResolve (node:internal/modules/esm/hooks:748:28), 1)
(9: resolve (node:internal/modules/esm/hooks:240:30), 1)
(10: handleMessage (node:internal/modules/esm/worker:199:24), 1)
(, 1)
(, 1)

Steps to reproduce:

1. XXX
   code --install-extension "c:\temp\ms-python.python-2025.8.1@win32-x64.vsix"

Behaviour

The error message occurs but the extension get's installed anyways

Steps to reproduce:

1. XXX

Diagnostic data

Output for Python in the Output panel (View→Output, change the drop-down the upper-right of the Output panel to Python)

XXX

Extension version: 2025.8.1
VS Code version: Code 1.101.0 (dfaf44141ea9deb3b4096f7cd6d24e00c147a4b1, 2025-06-11T15:00:50.123Z)
OS version: Windows_NT x64 10.0.22631
Modes:

• Python version (& distribution if applicable, e.g. Anaconda): 3.12.9
• Type of virtual environment used (e.g. conda, venv, virtualenv, etc.): System
• Value of the python.languageServer setting: Default

User Settings

languageServer: "Pylance"

Installed Extensions

Extension Name	Extension Id	Version
azure-repos	ms-	0.40.0
cmake-tools	ms-	1.21.36
code-spell-checker	str	4.0.47
copilot	Git	1.342.0
copilot-chat	Git	0.28.5
cpptools	ms-	1.26.3
csharp	ms-	2.84.19
data-workspace-vscode	ms-	0.6.3
datawrangler	ms-	1.22.0
debugpy	ms-	2025.8.0
devdock	Bos	0.1.0
docomment	k--	1.0.0
EditorConfig	Edi	0.17.4
git-graph	mhu	1.30.0
githistory	don	0.6.20
gitlens	eam	17.3.0
js-debug	ms-	1.100.1
js-debug-companion	ms-	1.1.3
jupyter	ms-	2025.6.0
jupyter-keymap	ms-	1.1.2
jupyter-renderers	ms-	1.3.0
live-server	ms-	0.4.15
LiveServer	rit	5.7.9
markdown-all-in-one	yzh	3.6.3
mssql	ms-	1.33.0
notepadplusplus-keybindings	ms-	1.0.7
path-intellisense	chr	2.10.0
powershell	ms-	2025.2.0
prettier-sql-vscode	inf	1.6.0
prettier-vscode	esb	11.0.0
python	ms-	2025.8.1
rainbow-csv	mec	3.20.0
remote-containers	ms-	0.417.0
remote-explorer	ms-	0.5.0
remote-repositories	ms-	0.42.0
remote-ssh	ms-	0.120.0
remote-ssh-edit	ms-	0.87.0
remote-wsl	ms-	0.99.0
remotehub	Git	0.64.0
rest-client	hum	0.25.1
sql-database-projects-vscode	ms-	1.5.3
vscode-azureappservice	ms-	0.26.2
vscode-azurefunctions	ms-	1.17.3
vscode-azureresourcegroups	ms-	0.11.0
vscode-azurestorage	ms-	0.16.5
vscode-azurevirtualmachines	ms-	0.6.9
vscode-containers	ms-	2.0.3
vscode-dotnet-runtime	ms-	2.3.6
vscode-firefox-debug	fir	2.15.0
vscode-js-profile-table	ms-	1.0.10
vscode-jupyter-cell-tags	ms-	0.1.9
vscode-jupyter-slideshow	ms-	0.1.6
vscode-pylance	ms-	2025.6.2
vscode-sql-formatter	adp	1.4.4
vscode-xml	red	0.29.0
vscode-yaml	red	1.18.0
vscodeintellicode	Vis	1.3.2
vsliveshare	ms-	1.0.5948

System Info

Item	Value
CPUs	Intel(R) Xeon(R) Platinum 8462Y+ (4 x 2800)
GPU Status	2d_canvas: unavailable_software canvas_oop_rasterization: disabled_off direct_rendering_display_compositor: disabled_off_ok gpu_compositing: disabled_software multiple_raster_threads: enabled_on opengl: disabled_off rasterization: disabled_software raw_draw: disabled_off_ok skia_graphite: disabled_off video_decode: disabled_software video_encode: disabled_software vulkan: disabled_off webgl: unavailable_software webgl2: unavailable_software webgpu: unavailable_software webnn: unavailable_software
Load (avg)	undefined
Memory (System)	16.00GB (6.53GB free)
Process Argv	--crash-reporter-id 6e48cb20-ee3a-4aa4-8079-28a562ce6772
Screen Reader	no
VM	100%

[eleanorjboyd]

Hello! What are you trying to do by installing the extension by vsix?

[hjrb]

Get it installed. Please stop doubting the reasons and start fixing the issue.

[mark-strasser-nnl]

Hello! What are you trying to do by installing the extension by vsix?

Answering for my use case - some proxied corporate networks do not have direct network access to the VSCode Marketplace. Downloading the VSIX files and installing from the command line is normal for these cases.

I have a similar issue when installing from a GitHub Actions workflow with a Windows Server 2025 runner.

[eleanorjboyd]

see microsoft/vscode-python-environments#420

[mark-strasser-nnl]

I resolved my issue by adding a "sleep" command between subsequent installs of extensions from the command line.

I don't believe it's related to this specific extension, at least not in my case.

See microsoft/vscode#256031