[Bug]: Netlify deploy failing due to missing netlify-handler.js

[azinod]

Version

System:
    OS: macOS 15.7.4
    CPU: (14) arm64 Apple M3 Max
    Memory: 301.03 MB / 36.00 GB
    Shell: 5.9 - /bin/zsh
  Browsers:
    Chrome: 145.0.7632.110
    Edge: 145.0.3800.70
    Firefox: 147.0.4
    Safari: 26.3
  npmPackages:
    @modern-js/app-tools: 3.0.2 => 3.0.2 
    @modern-js/runtime: 3.0.2 => 3.0.2 
    @modern-js/server-runtime: 3.0.2 => 3.0.2 
    @modern-js/tsconfig: 3.0.2 => 3.0.2

Details

We started getting issues to deply to Netlify after upgrading to v3.0.2

When I run MODERNJS_DEPLOY=netlify npx modern deploy, the generated output files in .netlify/functions include a netlify-handler.cjs, however when I deploy to netlify the function initalization fails because it is looking for netlify-handler.js (regular JS file, not CJS)

I am guessing the issue might have to do with the line below that tries to import netlify-handler.js instead of netlify-handler.cjs

modern.js/packages/solutions/app-tools/src/plugins/deploy/platforms/netlify.ts

Lines 141 to 143 in 5269eac

	let handlerCode = (
	await fse.readFile(path.join(__dirname, './netlify-handler.js'))
	).toString();

This is the error I get:

Feb 25, 02:55:57 PM: ERROR  Uncaught Exception 	{"errorType":"Runtime.ImportModuleError","errorMessage":"Error: Cannot find module './netlify-handler.js'\nRequire stack:\n- /var/task/index.js\n- /var/runtime/index.mjs","stack":["Runtime.ImportModuleError: Error: Cannot find module './netlify-handler.js'","Require stack:","- /var/task/index.js","- /var/runtime/index.mjs","    at _loadUserApp (file:///var/runtime/index.mjs:1192:17)","    at async UserFunction.js.module.exports.load (file:///var/runtime/index.mjs:1235:21)","    at async start (file:///var/runtime/index.mjs:1454:23)","    at async file:///var/runtime/index.mjs:1464:1"]}

Can you please check?

Reproduce link

Don't have one yet

Reproduce Steps

To test this, you need to setup a new project and a netlify app and test deploy to netlify using this build command: MODERNJS_DEPLOY=netlify npx modern deploy

[azinod]

I created script to replace netlify-handler.js by netlify-handler.cjs to test and got a different error:

Feb 25, 03:32:55 PM: ERROR  Uncaught Exception 	{"errorType":"Runtime.HandlerNotFound","errorMessage":"index.handler is undefined or not exported","stack":["Runtime.HandlerNotFound: index.handler is undefined or not exported","    at UserFunction.js.module.exports.load (file:///var/runtime/index.mjs:1238:15)","    at async start (file:///var/runtime/index.mjs:1454:23)","    at async file:///var/runtime/index.mjs:1464:1"]}

Reverting ModernJS to v2 fixes the issue, but we really wanted v3 since we are leveraging module-federation and SSR

[zllkjc]

Thanks for feedback, let's check it~

[azinod]

Hello @clChenLiang and @zllkjc,

I cloned this repository locally to test the changes from this PR and while the changes fix the initial issue, I faced a few other issues to get things actually running.

I put together this followup PR with the other changes that I had to do to have my ModernJS app properly deploy and run on Netlify as a Function.

The changes in the PR are probably not the best solutions to the issues I faced, but they at least serve to illustrate other potential issues that might need to be addressed and hint at what could be the proper solution to get them fixed.

Can you please take a look and see if they make sense?

[clChenLiang]

@azinod Hi, here we saw your pr, it seems fine.

The more available fixture will after my test, maybe to use a middleware to transfer the two request. It needs some time for us. Can you use your fork version to instead ModernJs if your problem can be fixed by.

As we see, the hono has set the request for a long time, and the old version ModernJs has not meet the compatibility problem. we will to find why this version

[azinod]

@clChenLiang thank you for checking this.

We already reverted to ModernJS v2.7.8 for the time being until we can get the definitive fix in the main ModernJS repository.

Can we keep this issue open for the time being so we can follow status updates?

Thank you!

[zllkjc]

@azinod Sure, keep this issue, we will check it asap~

[clChenLiang]

@azinod hi, after we carefully check. We found that make this error is the netlify function devide different runtime api version with the handler.cjs's export way.

and this make the hone received a plant object instead the Request:

The normal Request should be:

[clChenLiang]

We fixed in #8477.
If you check this commit not has other problem, we will publish in 2026-03-25

[azinod]

Thank you @clChenLiang for working on this, I will give it a shot this week.

[clChenLiang]

0.0.0-nightly-20260323162459
a nightly version

[kritb-earnin]

@clChenLiang Thanks for the update! I tested the fix using the nightly version, but I encountered the following error in my Netlify function logs:

ERROR  Error creating server: Error [ERR_MODULE_NOT_FOUND]: Cannot find package 'server' imported from /var/task/node_modules/@modern-js/utils/dist/cjs/cli/require.js
Did you mean to import "file:///var/task/server/modern.server.js"?
    at Object.getPackageJSONURL (node:internal/modules/package_json_reader:314:9)
    at packageResolve (node:internal/modules/esm/resolve:773:81)
    at moduleResolve (node:internal/modules/esm/resolve:859:18)
    at moduleResolveWithNodePath (node:internal/modules/esm/resolve:989:14)
    at defaultResolve (node:internal/modules/esm/resolve:1032:79)
    at #cachedDefaultResolve (node:internal/modules/esm/loader:731:20)
    at ModuleLoader.resolve (node:internal/modules/esm/loader:708:38)
    at ModuleLoader.getModuleJobForImport (node:internal/modules/esm/loader:310:38)
    at onImport.tracePromise.__proto__ (node:internal/modules/esm/loader:664:36)
    at TracingChannel.tracePromise (node:diagnostics_channel:350:14) {
  code: 'ERR_MODULE_NOT_FOUND'
}

Do you have any suggestions on how to resolve this?

Version

"@modern-js/app-tools": "0.0.0-nightly-20260323162459"
"@modern-js/runtime": "0.0.0-nightly-20260323162459" 
"@modern-js/server-runtime": "0.0.0-nightly-20260323162459"
"@modern-js/tsconfig": "0.0.0-nightly-20260323162459"

[clChenLiang]

@kritb-earnin could you gave an re produce env, or mvp code ?
Seem like your server.js file failed, if import not from your customer code, it might be another bug