@cleiter As the compiler API was changed between Kotlin 1.0 and 1.1, you need to use the compatible plugin version (1.1) when building with the new kotlinc

yan: so this means for compiler plugins it's not backwards compatible?

The functionality of the compiler plugins is backwards-compatible, but they use the compiler API that isn’t. By the way, can you provide some more details about your project configuration (PM is ok)?