Hi,
This has nothing to do with Gatling or Scala version.
You’re trying to use Scala’s for comprehension so you should probably try to read some tutorials first, eg https://docs.scala-lang.org/tour/for-comprehensions.html.
For comprehensions iterate over containers of the same type with the “<-” operator.
You have to switch the 2 lines in your for comprehension block and use an “=” instead of a <- for the (new) second line as you don’t want to iterate over an Int.