When I run Gulp Serve on a new web part I get several Error Messages

[Quietstormdee]

I'm new to SPFX and trying to work on my first hello world web part on my Mac, however I am getting these errors:

---

npm error gyp verb check python checking for Python executable "python" in the PATH
npm error gyp verb which failed Error: not found: python
npm error gyp verb which failed at getNotFoundError (/Users/submittername/node_modules/which/which.js:13:12)
npm error gyp verb which failed at F (/Users/submittername/node_modules/which/which.js:68:19)
npm error gyp verb which failed at E (/Users/submittername/node_modules/which/which.js:80:29)
npm error gyp verb which failed at /Users/submittername/node_modules/which/which.js:89:16
npm error gyp verb which failed at /Users/submittername/node_modules/isexe/index.js:42:5
npm error gyp verb which failed at /Users/submittername/node_modules/isexe/mode.js:8:5
npm error gyp verb which failed at FSReqCallback.oncomplete (node:fs:195:21)
npm error gyp verb which failed python Error: not found: python
npm error gyp verb which failed at getNotFoundError (/Users/submittername/node_modules/which/which.js:13:12)
npm error gyp verb which failed at F (/Users/submittername/node_modules/which/which.js:68:19)
npm error gyp verb which failed at E (/Users/submittername/node_modules/which/which.js:80:29)
npm error gyp verb which failed at /Users/submitternamenode_modules/which/which.js:89:16
npm error gyp verb which failed at /Users/submittername/node_modules/isexe/index.js:42:5
npm error gyp verb which failed at /Users/submittername/node_modules/isexe/mode.js:8:5
npm error gyp verb which failed at FSReqCallback.oncomplete (node:fs:195:21) {
npm error gyp verb which failed code: 'ENOENT'
npm error gyp verb which failed }
npm error gyp ERR! configure error
npm error gyp ERR! stack Error: Can't find Python executable "python", you can set the PYTHON env variable.
npm error gyp ERR! stack at PythonFinder.failNoPython (/Users/submittername/node_modules/node-gyp/lib/configure.js:484:19)
npm error gyp ERR! stack at PythonFinder. (/Users/submittername/node_modules/node-gyp/lib/configure.js:406:16)
npm error gyp ERR! stack at F (/Users/submittername/node_modules/which/which.js:68:16)
npm error gyp ERR! stack at E (/Users/submittername/node_modules/which/which.js:80:29)
npm error gyp ERR! stack at /Users/submittername/node_modules/which/which.js:89:16
npm error gyp ERR! stack at /Users/submittername/node_modules/isexe/index.js:42:5
npm error gyp ERR! stack at /Users/submittername/node_modules/isexe/mode.js:8:5
npm error gyp ERR! stack at FSReqCallback.oncomplete (node:fs:195:21)
npm error gyp ERR! System Darwin 24.6.0
npm error gyp ERR! command "/Users/submittername/.nvm/versions/node/v24.12.0/bin/node" "/Users/submittername/node_modules/node-gyp/bin/node-gyp.js" "rebuild" "--verbose" "--libsass_ext=" "--libsass_cflags=" "--libsass_ldflags=" "--libsass_library="
npm error gyp ERR! cwd /Users/submittername/node_modules/node-sass
npm error gyp ERR! node -v v24.12.0
npm error gyp ERR! node-gyp -v v3.8.0
npm error gyp ERR! not ok
npm error Build failed with error code: 1
npm error A complete log of this run can be found in: /Users/submittername/.npm/_logs/2025-12-28T05_07_50_546Z-debug-0.log

  _=+#####!       

###########| .-----------------------------------.
###/ (##|(@) | Congratulations! |

######| \ | Solution submittername

is created. |
###/ /###| (@) | Run gulp serve to play with it! |
####### ##| / '-----------------------------------'

/##|(@)

###########|
**=+####!

submittername@Mac ~ % gulp serve
Error: Cannot find module '@microsoft/sp-build-web'
Require stack:

• /Users/submittername/gulpfile.js
• /Users/submittername/.nvm/versions/node/v24.12.0/lib/node_modules/gulp-cli/lib/shared/require-or-import.js
• /Users/submittername/.nvm/versions/node/v24.12.0/lib/node_modules/gulp-cli/lib/versioned/^5.0.0/index.js
• /Users/submittername/.nvm/versions/node/v24.12.0/lib/node_modules/gulp-cli/index.js
• /Users/submittername/.nvm/versions/node/v24.12.0/lib/node_modules/gulp-cli/bin/gulp.js
  at Module._resolveFilename (node:internal/modules/cjs/loader:1421:15)
  at defaultResolveImpl (node:internal/modules/cjs/loader:1059:19)
  at resolveForCJSWithHooks (node:internal/modules/cjs/loader:1064:22)
  at Module._load (node:internal/modules/cjs/loader:1227:37)
  at TracingChannel.traceSync (node:diagnostics_channel:328:14)
  at wrapModuleLoad (node:internal/modules/cjs/loader:245:24)
  at Module.require (node:internal/modules/cjs/loader:1504:12)
  at require (node:internal/modules/helpers:152:16)
  at Object. (/Users/submitternamegulpfile.js:3:15)
  at Module._compile (node:internal/modules/cjs/loader:1761:14) {
  code: 'MODULE_NOT_FOUND',
  requireStack: [
  '/Users/submittername/gulpfile.js',
  '/Users/submittername/.nvm/versions/node/v24.12.0/lib/node_modules/gulp-cli/lib/shared/require-or-import.js',
  '/Users/submittername.nvm/versions/node/v24.12.0/lib/node_modules/gulp-cli/lib/versioned/^5.0.0/index.js',
  '/Users/submittername/.nvm/versions/node/v24.12.0/lib/node_modules/gulp-cli/index.js',
  '/Users/submittername/.nvm/versions/node/v24.12.0/lib/node_modules/gulp-cli/bin/gulp.js'
  ]
  }
  submittername@Mac ~ %

[Ashlesha-MSFT]

Hello @Quietstormdee,
Thank you for bringing this issue to our attention. We will look into it and get back to you shortly.
If you don’t receive a reply within two working days, please use this escalation form to escalate.

[Ashlesha-MSFT]

@Quietstormdee,
Thanks for the details. According to the SPFx Platform & Toolchain Compatibility Reference, SPFx 1.21+ supports Node.js 22 (LTS).
However, you are currently using Node 24, which is not supported by any SPFx version and causes build failures such as node-gyp, node-sass, and missing @microsoft/sp-build-web.
Please switch to a supported Node version:

nvm install 22
nvm use 22

On macOS, ensure Python is installed for node-gyp:

brew install python
npm config set python python3

Then clean and reinstall dependencies:

rm -rf node_modules package-lock.json
npm install

Finally, run:
gulp serve
This is a known environment compatibility issue and not related to your web part code.

[VesaJuvonen]

Thx @Ashlesha-MSFT on providing the guidance here.

@Quietstormdee - Please check the dev environment guidance based on following documentation. If there's any changes needed for these, feedback always welcome:

• Latest SPFx 1.21.1 using Heft - https://learn.microsoft.com/en-us/sharepoint/dev/spfx/set-up-your-development-environment
• Previous versions using Gulp - https://learn.microsoft.com/en-us/sharepoint/dev/spfx/set-up-your-development-environment-gulp-toolchain

As noted - Node.js 24 is not support currently and based on the error messages you provided, you are using v24 - which is the root cause of the issue.

Let us know if this got you unblocked. Thx.