(UnicodeConversionError) invalid encoding starting at

Newby to Elixir and Phoenix and seeing this error when run my phornix app. Any idea on how I can go about troubleshooting this issue?

** (UnicodeConversionError) invalid encoding starting at <<160, 55, 0, 0, 0, 0, 0, 0, 64, 0, 0, 0, 0, 0, 0, 0, 24, 195, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 64, 0, 56, 0, 9, 0, 64, 0, 27, 0, 26, 0, 6, 0, 0, 0, 5, 0, 0, 0, 64, 0, ...>>
    (elixir) src/elixir_utils.erl:128: :elixir_utils.conversion_error/3
    (elixir) lib/code.ex:813: Code.require_file/2
    (mix) lib/mix/tasks/run.ex:145: Mix.Tasks.Run.run/5
    (mix) lib/mix/tasks/run.ex:85: Mix.Tasks.Run.run/1
    (mix) lib/mix/task.ex:331: Mix.Task.run_task/3
    (mix) lib/mix/cli.ex:79: Mix.CLI.run_task/2

Does this happen for every project? Or only for a few of them? If this happens with a fresh project as well, can you please push such a project to github, gitlab or similar services?

Also please tell us what version of elixir, erlang and phx_new you are using. Your operating system might be interesting as well.