Potentially misleading error message when sparkR backend is not available

R interpreter is dying in my 0.10.0 instance, and the message shown in the cell after trying to execute it has the specific suggestion:

sparkR backend is dead, please try to increase spark.r.backendConnectionTimeout

This occurs in rlang/src/main/java/org/apache/zeppelin/r/RInterpreter.java:

      // render output with knitr
      if (rbackendDead.get()) {
        return new InterpreterResult(InterpreterResult.Code.ERROR,
            "sparkR backend is dead, please try to increase spark.r.backendConnectionTimeout");

      if (useKnitr) {
        zeppelinR.setInterpreterOutput(null);

If this is the real cause of all dead R backends this makes sense; if not, it could be a red herring.