FWIW, this behavior started for me at CDK v2.167.0. Perhaps the biggest change was the transition from using aws-sdk v2 to v3.

I believe the issue indeed has to do with some interaction with the @aws-sdk/client-s3, specifically because of a recent update to the @smithy/node-http-handler dependency around how it handles expect request headers with 100-continue.

I've created a repo the reproduces the problem and demonstrates that using a prior version of @smithy/node-http-handler works.

@gdtroszak Thanks, your solution worked for me.
I've had the same issue with @aws-sdk/client-s3 changing @smithy/node-http-handler version to 3.3.1 in deno.lock worked!

While @gdtroszak 's solution works in some cases, it doesn't apply to all s3 APIs with some failing with

TypeError [ERR_INVALID_ARG_TYPE]: The first argume
nt must be of type string or an instance of Buffer, ArrayBuffer, or Array or an Array-like Object. Received an instance of File
    at _from (ext:deno_node/internal/buffer.mjs:217:9)
    at Function.from (ext:deno_node/internal/buffer.mjs:229:10)
    at writeBody (file:///home/yohe/.local/share/ghjk/deno/npm/registry.npmjs.org/@smithy/node-http-handler/3.3.1/dist-cjs/index.js:189:28)
    at writeRequestBody (file:///home/yohe/.local/share/ghjk/deno/npm/registry.npmjs.org/@smithy/node-http-handler/3.3.1/dist-cjs/index.js:170:5)
    at eventLoopTick (ext:core/01_core.js:214:9) {
  code: "ERR_INVALID_ARG_TYPE",
  name: "TypeError",
  toString: [Function (anonymous)],
  "$metadata": { attempts: 1, totalRetryDelay: 0 }
}

Eagerly awaiting #27381 to land. You folks know any other workaround?

This still fails in Deno 2.1.4 but works in Node:

import { PutObjectCommand, S3Client } from '@aws-sdk/client-s3'

const s3 = new S3Client({
  ...
})

const uploadObject = async () => {
  try {
    const command = new PutObjectCommand({
      Bucket: BUCKET_NAME,
      Key: OBJECT_KEY,
      Body: OBJECT_CONTENT,
    })
    console.log('Uploading object...')

    const response = await s3.send(command)

    console.log('Upload successful:', response)
  } catch (error) {
    console.error('Error uploading object:', error)
  }
}

uploadObject()

I spent an entire day debugging this issue, and it turns out the problem lies with Deno. Unfortunately, this was the last thing I thought could be causing it.

This fails without errors, which is the scariest part.

Temporary fix for Deno 2.1.4:

import { S3Client } from '@aws-sdk/client-s3'
import { NodeHttpHandler } from 'npm:@smithy/[email protected]' // DOWNGRADE HERE

const s3 = new S3Client({
  requestHandler: new NodeHttpHandler(),
})

@taseenb what version of client-s3 is it that worked with [email protected] for you? I tried a few versions but I'm still seeing the TypeError from above.

Edit: nvm. Looks like I was already using 3.3.1 when I encountered the TypeError at first.

3.726.1 works

Later versions seem to have issues, but haven't tried again recently