Fetching error: UND_ERR_REQ_CONTENT_LENGTH_MISMATCH

[rodriabregu]

There is a (currently closed) issue with the use of Fetch inside NextJS as NextJS wraps the default fetch with its own implementation, which also happens in xior.

Sometimes in build-time and run-time use can generate this type of error:

[11:31:47.257] TypeError: fetch failed
[11:31:47.257]     at Object.fetch (node:internal/deps/undici/undici:11576:11) {
[11:31:47.257]   cause: RequestContentLengthMismatchError: Request body length does not match content-length header
[11:31:47.257]       at AsyncWriter.end (node:internal/deps/undici/undici:10355:19)
[11:31:47.258]       at writeIterable (node:internal/deps/undici/undici:10263:16) {
[11:31:47.258]     code: 'UND_ERR_REQ_CONTENT_LENGTH_MISMATCH'
[11:31:47.258]   }
[11:31:47.258] }

In my case, locally I have not been able to reproduce it, however in a project deployed in Docker is where I have had the problem in run-time use (With a custom Content-Length or not).

The is the issue I mentioned: Nextjs Issue

Xior version: 0.6.1, Next.js version: 15.0.2.

[suhaotian]

From the error message, Maybe check the code where put the content-length in headers or where put headers from request,

But due to Next.js already fixed the fetch issue, you can check here for Request body length does not match content-length header/UND_ERR_REQ_CONTENT_LENGTH_MISMATCH error:

vercel/next.js#55410

Also, you can add below code to check the error from which endpoint:

import xior from 'xior';

const http = xior.create();

http.plugins.use((adapter, instance) => {
  return async (config) => {
    try {
      return adapter(config);
    } catch (error: any) {
      console.log(`${config.method} ${config.url} error:`, error, config);
      throw error;
    }
  };
});

Thanks for reporting this issue!