** (Mix) Could not start application qrcode: exited in: :qrcode.start(:normal, )
** (EXIT) an exception was raised:
** (UndefinedFunctionError) function :qrcode.start/2 is undefined or private
(qrcode) :qrcode.start(:normal, )
(kernel) application_master.erl:273: :application_master.start_it_old/4
Unless you run your project via mix directly, you will need to specify it in :applications that it gets bundled in the artifact, and if the application has a mod key, it will be tried to properly started.
If you’re using distillery, you could configure the qrcode app to be loaded, but not started as a workaround. This means you should omit it from the applications list in mix.exs and in the rel/config.exs in the relevant release block use:
After there is already an uncommented MR which was intended to fix this issue for 9 months now, and a bug report telling about a similar problem as you since January '17, I do not expect my MR to get merged though.
Maybe I will find some time later to rebarize and hex that, but I have to check license as well first…