Getting this?
java.lang.NoSuchMethodError: play.api.libs.iteratee.Execution$Implicits$.trampoline()Lscala/concurrent/ExecutionContext;
Is your build.sbt including a dependency like this?
"org.reactivemongo" %% "play2-reactivemongo" % "0.12.6-play24"
And you're using playframework version 2.4 (2.4.6 for me specifically)?
Then fix the problem by changing your dependency to:
"org.reactivemongo" %% "play2-reactivemongo" % "0.12.6-play24" exclude("com.typesafe.play", "play-iteratees_2.11"),