We inherited an Elixir project. After a year of irritations, we re-wrote it in Go and never looked back.

The combinatorics of having to deal with two different string types, two different throws (catch vs rescue), two different versions of each function (exception throwing vs error returning) in most of the base libs, weak typing, weak documentation, and the constant churn of dependencies because the language developers like to change things "just because" (i.e. regular re-naming of built-in functions for "consistency"--several builds broken because they just had to add/remove an underscore in one identifier or another).

And when things go wrong, we'd often have to dig-down into Erlang errors and libs the same way we would with Java errors in Clojure, so now we have two languages we've got to get everyone up-to-speed on.

When it got to the point where we were avoiding point upgrades in fear of how much of our code it would break, it was clearly time to move on.