this was failing on Scala 3.0.2. maybe it will pass on 3.1.3-RC3?

nope. @lrytz perhaps you'd like to dig into this? else one or both of us can return to it after Dublin

it isn't clear to me offhand if this is a real problem or whether we just need to make the test use different expected results on different Scala versions?

Hmm... Scala 3 generates a slightly different classfile, which means a different generated SVUID if the file was compiled with Scala 2. What I would do is update the scala-3 version of the test (https://github.com/scala/scala-parallel-collections/blob/main/junit/src/test/scala-3/scala/SerializationStabilityTest.scala) so that it passes after this change. The risk that anyone is deserializing across different Scala 3 versions is probably 0.

okay will do