Version-Release number of selected component:
dnf-1.1.3-1.fc23

Additional info:
reporter:       libreport-2.6.2
cmdline:        /usr/bin/python3 -OO /bin/dnf copr enable jkoecny/kakoune
executable:     /bin/dnf
kernel:         4.2.5-300.fc23.x86_64
runlevel:       N 5
type:           Python3
uid:            0

Truncated backtrace:
request.py:1112:do_request_:TypeError: POST data should be bytes or an iterable of bytes. It cannot be of type str.

Traceback (most recent call last):
  File "/usr/lib/python3.4/site-packages/dnfpluginscore/lib.py", line 71, in urlopen
    librepo.download_url(url, fo.fileno(), handle)
  File "/usr/lib64/python3.4/site-packages/librepo/__init__.py", line 1517, in download_url
    return _librepo.download_url(handle, url, fd)
librepo.LibrepoException: (10, 'Status code: 404 for https://copr.fedoraproject.org/coprs/jkoecny/kakoune/repo/fedora-23/', 'Error HTTP/FTP status code')

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.4/site-packages/dnf-plugins/copr.py", line 249, in _download_repo
    f = dnfpluginscore.lib.urlopen(self, None, self.copr_url + api_path, 'w+')
  File "/usr/lib/python3.4/site-packages/dnfpluginscore/lib.py", line 73, in urlopen
    raise IOError(e.args[1])
OSError: Status code: 404 for https://copr.fedoraproject.org/coprs/jkoecny/kakoune/repo/fedora-23/

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/bin/dnf", line 35, in <module>
    main.user_main(sys.argv[1:], exit_code=True)
  File "/usr/lib/python3.4/site-packages/dnf/cli/main.py", line 198, in user_main
    errcode = main(args)
  File "/usr/lib/python3.4/site-packages/dnf/cli/main.py", line 84, in main
    return _main(base, args)
  File "/usr/lib/python3.4/site-packages/dnf/cli/main.py", line 136, in _main
    cli.run()
  File "/usr/lib/python3.4/site-packages/dnf/cli/cli.py", line 1091, in run
    return self.command.run(self.base.extcmds)
  File "/usr/lib/python3.4/site-packages/dnf-plugins/copr.py", line 138, in run
    self._download_repo(project_name, repo_filename, chroot)
  File "/usr/lib/python3.4/site-packages/dnf-plugins/copr.py", line 257, in _download_repo
    res = urllib.request.urlopen(self.copr_url + "/coprs/" + project_name, 'w+')
  File "/usr/lib64/python3.4/urllib/request.py", line 161, in urlopen
    return opener.open(url, data, timeout)
  File "/usr/lib64/python3.4/urllib/request.py", line 461, in open
    req = meth(req)
  File "/usr/lib64/python3.4/urllib/request.py", line 1112, in do_request_
    raise TypeError(msg)
TypeError: POST data should be bytes or an iterable of bytes. It cannot be of type str.

Local variables in innermost frame:
self: <urllib.request.HTTPSHandler object at 0x7f38ccfa4e10>
request: <urllib.request.Request object at 0x7f38ce482128>
data: 'w+'
msg: 'POST data should be bytes or an iterable of bytes. It cannot be of type str.'
host: 'copr.fedoraproject.org'