Internal Server Error on Non-POST w/ Body

[HassanAbouelela]

Verify canary release

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

Provide environment information

Operating System:
      Platform: win32
      Arch: x64
      Version: Windows 11 Home
    Binaries:
      Node: 20.5.1
      npm: N/A
      Yarn: N/A
      pnpm: N/A
    Relevant Packages:
      next: 13.4.14-canary.1
      eslint-config-next: 13.4.13
      react: 18.2.0
      react-dom: 18.2.0
      typescript: 5.1.6
    Next.js Config:
      output: N/A

Which area(s) of Next.js are affected? (leave empty if unsure)

Middleware / Edge (API routes, runtime)

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

https://codesandbox.io/p/sandbox/agitated-yonath-cy9nps

To Reproduce

1. Start the server provided in the codesandbox demo
2. Open a new terminal and run any of the following:

• curl localhost:3000/example -X GET -H "Content-Type: text/plain" -d "Test"
• curl localhost:3000/example -X GET -H "Content-Type: text/plain" -d ""
• curl localhost:3000/example -X DELETE -H "Content-Type: text/plain" -d ""

4. Observe curl output as: Internal Server Error. Observe exception in server.

Describe the Bug

Sending a request to an API route with a body and without the POST method causes an internal server error.

Exception:

TypeError: fetch failed
    at Object.fetch (/project/sandbox/node_modules/next/dist/compiled/undici/index.js:1:26669)
    at async invokeRequest (/project/sandbox/node_modules/next/dist/server/lib/server-ipc/invoke-request.js:21:12)
    at async invokeRender (/project/sandbox/node_modules/next/dist/server/lib/router-server.js:252:29)
    at async handleRequest (/project/sandbox/node_modules/next/dist/server/lib/router-server.js:445:24)
    at async requestHandler (/project/sandbox/node_modules/next/dist/server/lib/router-server.js:462:13)
    at async Server.<anonymous> (/project/sandbox/node_modules/next/dist/server/lib/start-server.js:116:13) {
  cause: RequestContentLengthMismatchError: Request body length does not match content-length header
      at write (/project/sandbox/node_modules/next/dist/compiled/undici/index.js:1:67105)
      at _resume (/project/sandbox/node_modules/next/dist/compiled/undici/index.js:1:66726)
      at resume (/project/sandbox/node_modules/next/dist/compiled/undici/index.js:1:65413)
      at connect (/project/sandbox/node_modules/next/dist/compiled/undici/index.js:1:65301) {
    code: 'UND_ERR_REQ_CONTENT_LENGTH_MISMATCH'
  }
}

Expected Behavior

Sending a GET or similar request with a body may or may not be correct behavior, however it should not be an error for the server. The server should either ignore the body, or return a 400 (or whatever is deemed appropriate).

Probably related: #deleteerro

Which browser are you using? (if relevant)

No response

How are you deploying your application? (if relevant)

Occurs in dev and production builds

[mogzol]

Also encountering this. It also happens with GET requests without a body if there is a Content-Length: 0 header, which should be valid

[mogzol]

I've had to roll back to 13.4.12 until this issue is fixed, since my app is running behind a load balancer which always adds the Content-Length header.

[davecarlson]

I did a PR for this yesterday, it's been merged overnight. Can you try by tagging next to the canary branch ( branch, not release as it's not made one yet)

[davecarlson]

try
v13.4.14-canary.2

[HassanAbouelela]

I believe that's #53843? I linked it in the original issue but the link broke. I believe that should fix the second two curl examples in the reproduction instructions, but the first will still fail.

[HassanAbouelela]

Tested with canary.2. The examples with empty bodies are fixed. The first is still broken.

[davecarlson]

Tested with canary.2. The examples with empty bodies are fixed. The first is still broken.
Thats good - just my PR only addressed empty content lengths i'm afraid.

There's a semi-related discussion i found on undici : nodejs/undici#35

[thienguen]

Also encountered this, have this have a work around. Though its funny that I try to do a POSTbut actually DELETE-ing something instead

[Paget96]

I've had to roll back to 13.4.12 until this issue is fixed, since my app is running behind a load balancer which always adds the Content-Length header.

I am on 13.4.12 and still have the same issue

[bkamapantula]

I encountered the same issue on the latest version.

Downgraded the version to 13.4.12 as noted here: #53882 (comment), that worked.

[meotimdihia]

Did we have any way to print which code lines or requests caused the problem?
Currently, it is impossible to debug.
Please share the solution on the self-hosted server if you had it.

---

edit: nvm, we just need to try to catch the requests.

[rahadkc]

I also facing the same issue but It seems it's fixed in 13.5.4 version. Thanks

[pranjanai]

I am on 13.5.6 and still having the same issue, "UND_ERR_REQ_CONTENT_LENGTH_MISMATCH" causing with "server action" while "revalidatingTag or revalidatingPath".

[milindgoel15]

Any update on this issue? Any possible workarounds?