anyone got news about this issue ? https://github.com/mockito/mockito/issues/1152 this is quite blocking to me.

Since it looks like ByteBuddy is not going to be patched soon, we hope to patch Kotlin compiler in the next update. Here is the issue to track: https://youtrack.jetbrains.com/issue/KT-19713

feels strange to me, kotlin byte code seems legit to me

It is legit. ByteBuddy simply has unnecessarily strict checks on frames (at least for its usage in Mockito). Removing those checks makes Mockito work with Kotlin’s bytecode, but that patch to ByteBuddy was rejected.