EBUSY: resource busy error during automated update `npm install`

[kamranayub]

When getting an update notification, I consistently get the following error and have to manually run npm install. Originally, I thought it was with the playground server running but as you can see, this was a fresh start.

One thing I noticed as far as order of logs, is that the server gets started and then I receive the npm error. So not sure if there's a missing await or something like that before npm install is actually finished before starting the server.

❯ npm start

> start
> npx --prefix ./epicshop epicshop start

🐨 Welcome to the workshop, subka!
Supported keys:
  o - open workshop app
  u - update workshop
  r - restart workshop app
  k - Kody kudos 🐨
  q - exit (or Ctrl+C)


 🎉  There are updates available for this workshop repository.  🎉

To get the updates, press the "u" key

To view a diff, check:
   https://github.com/epicweb-dev/mcp-fundamentals/compare/0a47348...ab402bf 

To dismiss this notification, press the "d" key


🔄 Update requested from terminal. Running update and restarting app process...

👀 Checking for updates...
👜 Stashing uncommitted changes...
⬇️ Pulling latest changes...
👜 re-applying stashed changes...
📦 Re-installing dependencies...

> postinstall
> cd ./epicshop && npm install

🐨  Let's get learning!
Local:            http://localhost:5639
On Your Network:  http://172.23.96.1:5639

npm error code EBUSY
npm error syscall rename
npm error path E:\Development\Contrib\mcp-fundamentals\epicshop\node_modules\@epic-web\workshop-app
npm error dest E:\Development\Contrib\mcp-fundamentals\epicshop\node_modules\@epic-web\.workshop-app-dd77a4NT
npm error errno -4082
npm error EBUSY: resource busy or locked, rename 'E:\Development\Contrib\mcp-fundamentals\epicshop\node_modules\@epic-web\workshop-app' -> 'E:\Development\Contrib\mcp-fundamentals\epicshop\node_modules\@epic-web\.workshop-app-dd77a4NT'

Environment

• Windows 11, 64-bit
• VS Code terminal
• Node 24.0.1
• npm 11.3.0

[kentcdodds]

This is a new one. I haven't seen anybody have issue with an update like this before. One workaround would be to stop the server and then run the update script manually:

npx --prefix ./epicshop epicshop update

I'm not sure what to do to fix this so it works seamlessly for you. I'll leave it open and take a look at it at a future time.

[kamranayub]

Wonder if it might be due to having multiple instances of VS Code open?

• Instance 1: MCP Fundamentals repo -> Terminal is running npm start
• Instance 2: Playground directory

If VS Code is running npm start in its Terminal, perhaps it is holding onto resources in the node_modules.

One way to test this is for me to run the app in a separate terminal instance outside VS Code and see if the next update works. 🤔

[kamranayub]

OK, I just tried that with the latest update. Closed VS Code and stopped running server. Left only my Playground instance up.

New Windows PowerShell terminal output, I see a different error which is interesting.

mcp-fundamentals on  main [!⇣] via  v24.0.1
❯ npm start

> start
> npx --prefix ./epicshop epicshop start

🐨 Welcome to the workshop, subka!
Supported keys:
  o - open workshop app
  u - update workshop
  r - restart workshop app
  k - Kody kudos 🐨
  q - exit (or Ctrl+C)


 🎉  There are updates available for this workshop repository.  🎉

To get the updates, press the "u" key

To view a diff, check:
   https://github.com/epicweb-dev/mcp-fundamentals/compare/833d5dc...feff0c1

To dismiss this notification, press the "d" key

🐨  Let's get learning!
Local:            http://localhost:5639
On Your Network:  http://172.23.96.1:5639


🔄 Update requested from terminal. Running update and restarting app process...

👀 Checking for updates...
👜 Stashing uncommitted changes...
⬇️ Pulling latest changes...
👜 re-applying stashed changes...
📦 Re-installing dependencies...

> postinstall
> cd ./epicshop && npm install

npm error Cannot read properties of undefined (reading 'spec')
npm error A complete log of this run can be found in: C:\Users\subka\AppData\Local\npm-cache\_logs\2025-09-24T14_57_51_163Z-debug-0.log
npm error code 1
npm error path E:\Development\Contrib\mcp-fundamentals
npm error command failed
npm error command C:\WINDOWS\system32\cmd.exe /d /s /c cd ./epicshop && npm install
npm error A complete log of this run can be found in: C:\Users\subka\AppData\Local\npm-cache\_logs\2025-09-24T14_57_49_329Z-debug-0.log
❌ Command failed with exit code 1: npm install
Update failed. Please try again or see the repo for manual setup.

npm log:

19 verbose stack TypeError: Cannot read properties of undefined (reading 'spec')
19 verbose stack     at updateNodes (C:\Users\subka\AppData\Roaming\fnm\node-versions\v24.0.1\installation\node_modules\npm\node_modules\@npmcli\arborist\lib\arborist\reify.js:1326:44)
19 verbose stack     at [saveIdealTree] (C:\Users\subka\AppData\Roaming\fnm\node-versions\v24.0.1\installation\node_modules\npm\node_modules\@npmcli\arborist\lib\arborist\reify.js:1495:11)
19 verbose stack     at Arborist.reify (C:\Users\subka\AppData\Roaming\fnm\node-versions\v24.0.1\installation\node_modules\npm\node_modules\@npmcli\arborist\lib\arborist\reify.js:147:31)
19 verbose stack     at async Install.exec (C:\Users\subka\AppData\Roaming\fnm\node-versions\v24.0.1\installation\node_modules\npm\lib\commands\install.js:149:5)
19 verbose stack     at async Npm.exec (C:\Users\subka\AppData\Roaming\fnm\node-versions\v24.0.1\installation\node_modules\npm\lib\npm.js:208:9)
19 verbose stack     at async module.exports (C:\Users\subka\AppData\Roaming\fnm\node-versions\v24.0.1\installation\node_modules\npm\lib\cli\entry.js:67:5)
20 error Cannot read properties of undefined (reading 'spec')

Wonder if it has to do with privileges? 🤔 Next time I'll try escalating the PowerShell to admin. I don't love that though 😓

[kamranayub]

Nope, administrator prompt has the same issue as the original running in VS Code.

Administrator in mcp-fundamentals on  main [!⇣] via  v24.0.1
❯ npm start

> start
> npx --prefix ./epicshop epicshop start

🐨 Welcome to the workshop, subka!
Supported keys:
  o - open workshop app
  u - update workshop
  r - restart workshop app
  k - Kody kudos 🐨
  q - exit (or Ctrl+C)

🐨  Let's get learning!
Local:            http://localhost:5639
On Your Network:  http://172.23.96.1:5639


🔄 Update requested from terminal. Running update and restarting app process...

👀 Checking for updates...
👜 Stashing uncommitted changes...
⬇️ Pulling latest changes...
👜 re-applying stashed changes...
📦 Re-installing dependencies...

> postinstall
> cd ./epicshop && npm install

npm error code EBUSY
npm error syscall rename
npm error path E:\Development\Contrib\mcp-fundamentals\epicshop\node_modules\@epic-web\workshop-app
npm error dest E:\Development\Contrib\mcp-fundamentals\epicshop\node_modules\@epic-web\.workshop-app-dd77a4NT
npm error errno -4082
npm error EBUSY: resource busy or locked, rename 'E:\Development\Contrib\mcp-fundamentals\epicshop\node_modules\@epic-web\workshop-app' -> 'E:\Development\Contrib\mcp-fundamentals\epicshop\node_modules\@epic-web\.workshop-app-dd77a4NT'
npm error A complete log of this run can be found in: C:\Users\subka\AppData\Local\npm-cache\_logs\2025-09-24T15_56_15_500Z-debug-0.log
npm error code 4294963214
npm error path E:\Development\Contrib\mcp-fundamentals
npm error command failed
npm error command C:\WINDOWS\system32\cmd.exe /d /s /c cd ./epicshop && npm install
npm error A complete log of this run can be found in: C:\Users\subka\AppData\Local\npm-cache\_logs\2025-09-24T15_56_13_654Z-debug-0.log
❌ Command failed with exit code 4294963214: npm install
Update failed. Please try again or see the repo for manual setup.

So I think I've ruled out differences in VS Code terminal and privileges/permissions. Another cause could be Node 24/npm version I'm using 🤷 I could close out ALL instances of VS Code just to rule that out too.

[kentcdodds]

I think the core problem here is that we're replacing files that are actively being run. Specifically the CLI. So maybe if you were to install the CLI globally it might work... Try it this way from within the root of the mcp-fundamentals repo:

npx @epic-web/workshop-cli start --app-location ./epicshop/node_modules/@epic-web/workshop-app

It's possible that I will make doing this the default or at least explore that idea a little bit more. I really like having the repository control the version of the workshop CLI and app, but I also want you to have a good experience!

[kamranayub]

@kentcdodds that almost works but then I get a Zod error, possibly due to some network request/response going on in the background.

This is without pressing anything; just leaving it alone. Happens right away and exits the CLI.

Edit: Oh weird, I'm getting it normally too 😅 Might be unrelated.

mcp-fundamentals on  main [!⇣] via  v24.0.1
❯ npx @epic-web/workshop-cli start --app-location ./epicshop/node_modules/@epic-web/workshop-app
🐨 Welcome to the workshop, subka!
Supported keys:
  o - open workshop app
  u - update workshop
  r - restart workshop app
  k - Kody kudos 🐨
  q - exit (or Ctrl+C)


 🎉  There are updates available for this workshop repository.  🎉

To get the updates, press the "u" key

To view a diff, check:
   https://github.com/epicweb-dev/mcp-fundamentals/compare/15d48c7...b39967f

To dismiss this notification, press the "d" key

🐨  Let's get learning!
Local:            http://localhost:5639
On Your Network:  http://172.23.96.1:5639

This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). The promise rejected with the reason:
ZodError: [
  {
    "code": "invalid_type",
    "expected": "object",
    "received": "null",
    "path": [],
    "message": "Expected object, received null"
  }
]
    at Object.get error [as error] (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/zod/v3/types.js:39:31)
    at ZodObject.parse (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/zod/v3/types.js:114:22)
    at getFreshValue (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/workshop-utils/src/epic-api.server.ts:611:36)
    at processTicksAndRejections (node:internal/process/task_queues:105:5)
    at getFreshValue (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/cachified/src/getFreshValue.ts:17:24)
    at Module.cachified (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/cachified/src/cachified.ts:94:17)
    at async Promise.all (index 0)
    at getProgress (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/workshop-utils/src/epic-api.server.ts:373:6)
    at async Promise.all (index 1)
    at warmCache (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/workshop-utils/src/epic-api.server.ts:846:2)
ZodError: [
  {
    "code": "invalid_type",
    "expected": "object",
    "received": "null",
    "path": [],
    "message": "Expected object, received null"
  }
]
    at Object.get error [as error] (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/zod/v3/types.js:39:31)
    at ZodObject.parse (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/zod/v3/types.js:114:22)
    at getFreshValue (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/workshop-utils/src/epic-api.server.ts:611:36)
    at processTicksAndRejections (node:internal/process/task_queues:105:5)
    at getFreshValue (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/cachified/src/getFreshValue.ts:17:24)
    at Module.cachified (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/cachified/src/cachified.ts:94:17)
    at async Promise.all (index 0)
    at getProgress (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/workshop-utils/src/epic-api.server.ts:373:6)
    at async Promise.all (index 1)
    at warmCache (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/workshop-utils/src/epic-api.server.ts:846:2)
Unhandled Rejection for:  Promise {
  <rejected> ZodError: [
    {
      "code": "invalid_type",
      "expected": "object",
      "received": "null",
      "path": [],
      "message": "Expected object, received null"
    }
  ]
      at Object.get error [as error] (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/zod/v3/types.js:39:31)
      at ZodObject.parse (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/zod/v3/types.js:114:22)
      at getFreshValue (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/workshop-utils/src/epic-api.server.ts:611:36)
      at processTicksAndRejections (node:internal/process/task_queues:105:5)
      at getFreshValue (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/cachified/src/getFreshValue.ts:17:24)
      at Module.cachified (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/cachified/src/cachified.ts:94:17)
      at async Promise.all (index 0)
      at getProgress (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/workshop-utils/src/epic-api.server.ts:373:6)
      at async Promise.all (index 1)
      at warmCache (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/workshop-utils/src/epic-api.server.ts:846:2) {
    issues: [ [Object] ],
    addIssue: [Function (anonymous)],
    addIssues: [Function (anonymous)],
    errors: [ [Object] ]
  }
}
With the reason:  ZodError: [
  {
    "code": "invalid_type",
    "expected": "object",
    "received": "null",
    "path": [],
    "message": "Expected object, received null"
  }
]
    at Object.get error [as error] (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/zod/v3/types.js:39:31)
    at ZodObject.parse (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/zod/v3/types.js:114:22)
    at getFreshValue (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/workshop-utils/src/epic-api.server.ts:611:36)
    at processTicksAndRejections (node:internal/process/task_queues:105:5)
    at getFreshValue (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/cachified/src/getFreshValue.ts:17:24)
    at Module.cachified (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/cachified/src/cachified.ts:94:17)
    at async Promise.all (index 0)
    at getProgress (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/workshop-utils/src/epic-api.server.ts:373:6)
    at async Promise.all (index 1)
    at warmCache (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/workshop-utils/src/epic-api.server.ts:846:2) {
  issues: [
    {
      code: 'invalid_type',
      expected: 'object',
      received: 'null',
      path: [],
      message: 'Expected object, received null'
    }
  ],
  addIssue: [Function (anonymous)],
  addIssues: [Function (anonymous)],
  errors: [
    {
      code: 'invalid_type',
      expected: 'object',
      received: 'null',
      path: [],
      message: 'Expected object, received null'
    }
  ]
}
second error, exiting
ZodError: [
  {
    "code": "invalid_type",
    "expected": "object",
    "received": "null",
    "path": [],
    "message": "Expected object, received null"
  }
]
    at Object.get error [as error] (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/zod/v3/types.js:39:31)
    at ZodObject.parse (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/zod/v3/types.js:114:22)
    at getFreshValue (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/workshop-utils/src/epic-api.server.ts:611:36)
    at processTicksAndRejections (node:internal/process/task_queues:105:5)
    at getFreshValue (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/cachified/src/getFreshValue.ts:17:24)
    at Module.cachified (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/cachified/src/cachified.ts:94:17)
    at async Promise.all (index 0)
    at getProgress (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/workshop-utils/src/epic-api.server.ts:373:6)
    at async Promise.all (index 1)
    at warmCache (file:///E:/Development/Contrib/mcp-fundamentals/epicshop/node_modules/@epic-web/workshop-utils/src/epic-api.server.ts:846:2) {
  issues: [
    {
      code: 'invalid_type',
      expected: 'object',
      received: 'null',
      path: [],
      message: 'Expected object, received null'
    }
  ],
  addIssue: [Function (anonymous)],
  addIssues: [Function (anonymous)],
  errors: [
    {
      code: 'invalid_type',
      expected: 'object',
      received: 'null',
      path: [],
      message: 'Expected object, received null'
    }
  ]
}

[kentcdodds]

Yeah, that was unrelated. It's fixed now though!

[kentcdodds]

Was this ever resolved or is it still a problem for you?

[kamranayub]

No, it's still an issue but the workaround is easy enough 🤷‍♂️