Middleware is incompatible with `server-only

[barryengineerapart]

Link to the code that reproduces this issue or a replay of the bug

https://codesandbox.io/p/sandbox/vigorous-ace-sx277k?file=/middleware.ts:1,1

To Reproduce

If I create the following middlerware.ts with contents:

import "server-only";
export function middleware() {}

I get the following error:

Server Error
Error: This module cannot be imported from a Client Component module. It should only be used from a Server Component.
This error happened while generating the page. Any console logs will be displayed in the terminal window.
Call Stack
<unknown>
node_modules/server-only/index.js (1:0)
eval
node_modules/server-only/index.js (1:6)
(middleware)/./node_modules/server-only/index.js
file:///Users/adriang/code/mid-test/.next/server/middleware.js (435:1)
__webpack_require__
file:///Users/adriang/code/mid-test/.next/server/edge-runtime-webpack.js (37:33)
fn
file:///Users/adriang/code/mid-test/.next/server/edge-runtime-webpack.js (268:21)
eval
webpack-internal:///(middleware)/./middleware.ts (5:69)
(middleware)/./middleware.ts
file:///Users/adriang/code/mid-test/.next/server/middleware.js (29:1)
__webpack_require__
file:///Users/adriang/code/mid-test/.next/server/edge-runtime-webpack.js (37:33)
fn
file:///Users/adriang/code/mid-test/.next/server/edge-runtime-webpack.js (268:21)
eval
webpack-internal:///(middleware)/./node_modules/next/dist/build/webpack/loaders/next-middleware-loader.js (7:72)
(middleware)/./node_modules/next/dist/build/webpack/loaders/next-middleware-loader.js?absolutePagePath=%2FUsers%2Fadriang%2Fcode%2Fmid-test%2Fmiddleware.ts&page=%2Fmiddleware&rootDir=%2FUsers%2Fadriang%2Fcode%2Fmid-test&matchers=&preferredRegion=&middlewareConfig=e30%3D!
file:///Users/adriang/code/mid-test/.next/server/middleware.js (18:1)

Current vs. Expected behavior

The expectation is that this would not throw the above exception since I am under the impression that middleware would only run on the server.

It doesn't make sense to run them client-side, from docs:

Middleware allows you to run code before a request is completed. Then, based on the incoming request, you can modify the response by rewriting, redirecting, modifying the request or response headers, or responding directly.

Verify canary release

• I verified that the issue exists in the latest Next.js canary release

Provide environment information

Operating System:
      Platform: darwin
      Arch: arm64
      Version: Darwin Kernel Version 22.6.0: Wed Jul  5 22:21:53 PDT 2023; root:xnu-8796.141.3~6/RELEASE_ARM64_T6020
    Binaries:
      Node: 18.16.0
      npm: 9.5.1
      Yarn: N/A
      pnpm: N/A
    Relevant Packages:
      next: 13.4.12
      eslint-config-next: 13.4.12
      react: 18.2.0
      react-dom: 18.2.0
      typescript: 5.1.6
    Next.js Config:
      output: N/A

Which area(s) are affected? (Select all that apply)

Middleware / Edge (API routes, runtime)

Additional context

No response

[balazsorban44]

Duplicate of #54549

[github-actions]

This closed issue has been automatically locked because it had no new activity for 2 weeks. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.