Arnout Engelen

> What about upgrading scala-xml only if using Scala 3? We did that in play-ws and twirl: Yes, we plan to do that in https://github.com/akka/akka-http/pull/4079/files#diff-ad2642dc77b3679e4ad2c7d3b2f59a2dcf48c1bf5b93a558a4fa44828315a34cR53 as well.

> 1: code doesn't compile (missing an import and declaration of an implicit materializer) Hmm, seems to work for me: https://github.com/raboof/akka-http-4077 . Can you spot what was the difference with...

Thanks for your detailed report - this sounds rather serious. I have tried to reproduce it in isolation (https://github.com/raboof/akka-http-4122) but so far have not yet been able to. Could you...

> I will try to keep adding more stuff to your example and see if I can manage to reproduce it in the end. That is great, thanks!

Thanks for the investigation! > I also found this ticket: #3920 which somehow seems to be related. That sounds like potentially the same issue indeed - would be great if...

I converted https://github.com/raboof/akka-http-4122 to Scala 2 now, if that helps :)

> I managed to reproduce it by adding an integration test with your prototype. I had to make some changes in terms of certificates to make it closer to our...

You are still listed 'Awaiting adibaranga’s response' - I guess you need to accept the invitation somehow?

> Did you manage to reproduce the issue? Yes I have, thanks a lot! I have been looking into the issue, and the good news is I think there is...

By spelling out the implicit more, uh, explicitly: ``` implicitly[ToResponseMarshaller[Future[List[Dummy]]]] ``` We get a better error message: ``` [error] |no implicit argument of type akka.http.scaladsl.marshalling.ToResponseMarshaller[ [error] | concurrent.Future[List[Dummy]] [error] |]...