For reproduction of bugs considering this distillery issue.

It seems that distillery only works properly with conform when the ERTS system is included. Otherwise the release will crash on initialization. This can be reproduced using

mix release --env=with_erts

or respective

mix release --env=without_erts

where the latter generated release will crash on startup because external modules can't be accessed from the conform schema.

Note: The error changes when you remove the _build folder between building the releases. Without removing the folder a crash dump message will pop up. If you removed the folder in between then the following should be printed:

** (UndefinedFunctionError) function DistilleryTest.Conform.negate/1 is undefined (module DistilleryTest.Conform is not available)
    DistilleryTest.Conform.negate(false)
    (conform) lib/conform/translate.ex:183: Conform.Translate.apply_transforms/2
    (conform) lib/conform/translate.ex:95: Conform.Translate.apply_schema/2
    (conform) lib/conform/translate.ex:65: Conform.Translate.to_config/3
    (conform) lib/conform.ex:92: Conform.process/1
    (elixir) lib/kernel/cli.ex:76: anonymous fn/3 in Kernel.CLI.exec_fun/2

The mentioned module is of course not missing and is also used when the ERTS system is included.