select(df, c("col1", "col2")) fails

The help page for 'select' gives an example of
select(df, c("col1", "col2"))

However, this fails with assertion:

java.lang.AssertionError: assertion failed
at scala.Predef$.assert(Predef.scala:165)
at org.apache.spark.api.r.SerDe$.readStringBytes(SerDe.scala:92)
at org.apache.spark.api.r.SerDe$.readString(SerDe.scala:99)
at org.apache.spark.api.r.SerDe$.readTypedObject(SerDe.scala:63)
at org.apache.spark.api.r.SerDe$.readObject(SerDe.scala:52)
at org.apache.spark.api.r.RBackendHandler$$anonfun$readArgs$1.apply(RBackendHandler.scala:182)
at org.apache.spark.api.r.RBackendHandler$$anonfun$readArgs$1.apply(RBackendHandler.scala:181)

And then none of the functions will work with following error:
> head(df)
Error in if (returnStatus != 0) { : argument is of length zero