This change broke serialization of case classes with multiple arguments list, is it intended?

I don't see how it can break the JSON serialization, as such classes were just not supported before (compilation error), while the API is unchanged.

it was working before http://scastie.org/21867
doesn't work now http://scastie.org/21868 :(

Writes could have "accidentally" worked with such multi parameters constructors, even if never documented, but the reads and format didn't and cannot. The macros now enforce explicitly and in all the case this same restriction: no multi param constructor for case classes (break coherence between apply/unapply.

i'm just pointing out that 2.5.5 is no longer compatible with 2.5.4

It's binary and API compatible, and also fixes macro incoherencies about an undocumented/not recommanded case. Not it can be said to "break", but it can be documented now.

i've created an issue #6476 as it is very clearly a breaking change for us

I understand that the restrictions described previously in this thread applies for more than one parameter lists. But I'm also getting the 'No apply function found matching unapply parameters' message when I have a generic case class more than 1 generic parameters in the same param list. Like so:

case class Interval[T](base: T, tolerance: Option[T])

implicit val intFmt: Format[Interval[Int]] = Json.format[Interval[Int]]

I would expect that to work, or?

@kpmeen I guess this is more related to #5261: the following case class with multiple generic parameter (not recursive) is working fine. There is no change about that for now.

case class Interval[T](base: T, tolerance: T)

ah...ok. Thanks @cchantep.