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VS Code shows “Unbound breakpoint” when setting breakpoints in Node.js core files under lib/internal #5103
Description
Node.js Version
v24.3.0
NPM Version
11.4.2
Operating System
Darwin Scohearts-MacBook-Pro.local 24.6.0 Darwin Kernel Version 24.6.0: Mon Jul 14 11:30:40 PDT 2025; root:xnu-11417.140.69~1/RELEASE_ARM64_T6041 arm64
Subsystem
Other
Description
When I try to debug Node.js core by setting breakpoints directly in files under lib/internal/* (opened from the Node.js source checkout) using VS Code, those breakpoints remain Unbound and never hit.
Minimal Reproduction
.vscode/launch.json
{
"version": "0.2.0",
"configurations": [
{
"type": "cppdbg",
"request": "launch",
"name": "lldb-node",
"program": "${workspaceFolder}/out/Debug/node",
"args": [
"--inspect-brk=9229",
"--import=${workspaceFolder}/mytest/register.mjs",
"${workspaceFolder}/mytest/index.js"
],
"cwd": "${workspaceRoot}",
"environment": [
{
"name": "NODE_DEBUG",
"value": "*"
}
],
"MIMode": "lldb"
},
{
"name": "js-attach",
"type": "node",
"request": "attach",
"port": 9229,
"restart": true,
"skipFiles": [],
"smartStep": false
}
],
"compounds": [
{
"name": "C++ + JS",
"configurations": [
"lldb-node",
"js-attach"
]
}
]
}
Output
No response
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Activity
avivkeller commentedon Oct 9, 2025
The node executable bundles all of its source files. Adding breakpoints to the
libfolder, which, are the un-bundled files, won't do anything.However, if you compile the node with https://github.com/nodejs/node/blob/main/BUILDING.md#loading-js-files-from-disk-instead-of-embedding, VSCode breakpoints will work.