Error on ls: `Transport endpoint is not connected`

I've got this error on Fedora-25 x86_64. Steps to reproduce:

$ ./marcfs ~/Mail.Ru -o username=***@mail.ru,password=***
$ LANG=C ls ~/Mail.Ru/
ls: reading directory '/home/slowpoke/Mail.Ru/': Software caused connection abort

Password is 100% correct.

Got any tips how to debug this error?