Potential bug in POST HTTPS request with formParam's for Gatling versions 3.0.0+

Hello there Gatling community!

I’ve been using Gatling for the last months to write component & performance tests and stumbled across this issue that made me go back to previous Gatling versions to work.

My current environment is:

  • OpenJDK Runtime Environment (Zulu (build 1.8.0_212-b04)

The scenario
I am performing a POST request to a HTTPS endpoint passing some Form params with it.

Doing this with Gatling version 3.x.x.

The code looks like this:

import io.gatling.core.Predef._
import io.gatling.http.Predef._

class GetSmSessionSimulation2 extends Simulation {

  val loginChallenge =
    scenario("Get login challenge details")
      .formParam("sfid", "0401458997_53")
      .formParam("challenge", "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")
      .formParam("secret", "121212")
      .exec(session => {


And I see this in a log:

POST /e2e_sim HTTP/1.1
accept: */*
origin: https://vm00006525.nl.eu.acme.com:9100
host: vm00006525.nl.eu.acme.com:9100
content-type: application/x-www-form-urlencoded
content-length: 615, content=null}
14:24:07.496 [gatling-http-1-2] DEBUG io.netty.handler.ssl.SslHandler - [id: 0x7d6f9fe8, L:/ - R:vm00006525.nl.eu.acme.com/] HANDSHAKEN: TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256

Pay attention to the content=null part, that looks wrong. After that, Gatling tries many times to send the request until it times out like this:

Login: KO i.g.h.c.i.RequestTimeoutException: Request timeout to vm00006525.nl.eu.acme.com/ after 60000 ms

Doing this with Gatling version 3.x.x.

The actual version number matters. Please make sure you’re running latest version (3.2.0).

Pay attention to the content=null part, that looks wrong.

No, it’s correct.You’ve truncated the first line that would show you’re sending a FullHttpRequest that already contains the body bytes, and not a simple HttpRequest where body bytes would be written on the Netty pipeline as a distinct object (eg multipart or file upload).

As I said earlier, provide a sample we can run on our side so we can reproduce and investigate.
Without such sample, we can’t do much more than playing riddles.

At the very least, please provide the full TRACE logs, possibly privately.