Ok found a method to replicate the missing stacktrace:

boot.user=> (let [x (fn [] (/ nil 1)) cnt0 20000] (loop [cnt 0] (when-not (= cnt cnt0) (recur (try (x) (catch Exception e (print ".") (flush) (if (seq (.getStackTrace e)) (inc cnt) (do (println "No stacktrace at" cnt) cnt0))))))))
............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................No stacktrace at 699

@flyboarder Think I fixed it https://github.com/boot-clj/bootstrap/pull/4

Tests are failing apparently. Should I create a docker cloud account to see the info?