Build problem: cannot access router.RoutesPrefix

Hi, below is a snippet of the output while building The Yahoo Kafka-manager. It says it cannot access router.RoutesPrefix, but I have no idea what it means or what I can or should do about it.

I ran ./sbt dist clean , as per the documentation.

Anyone an idea what could be investigated here, or what the problem could be? What does this message mean anyway?

[info] Done updating.
[warn] There may be incompatibilities among your library dependencies; run ‘evicted’ to see detailed eviction warnings.
[info] Wrote /data/kafka-manager/target/scala-2.12/kafka-manager_2.12-2.0.0.2.pom
Warning: node.js detection failed, sbt will use the Rhino based Trireme JavaScript engine instead to run JavaScript assets compilation, which in some cases may be orders of magnitude slower than using node.js.
[info] Main Scala API documentation to /data/kafka-manager/target/scala-2.12/api…
[info] Compiling 131 Scala sources and 2 Java sources to /data/kafka-manager/target/scala-2.12/classes …
[info] Non-compiled module ‘compiler-bridge_2.12’ for Scala 2.12.8. Compiling…
[info] Compilation completed in 12.805s.
model contains 604 documentable templates
[info] Main Scala API documentation successful.
[info] Packaging /data/kafka-manager/target/scala-2.12/kafka-manager_2.12-2.0.0.2-javadoc.jar …
[info] Done packaging.
[info] Packaging /data/kafka-manager/target/scala-2.12/kafka-manager_2.12-2.0.0.2-web-assets.jar …
[error] /data/kafka-manager/conf/routes: cannot access router.RoutesPrefix
[warn] javac exited with exit code 1
[info] Done packaging.
[error] (Compile / compileIncremental) javac returned non-zero exit code
[error] Total time: 202 s, completed Dec 6, 2019 4:13:35 PM

No one here to help out?