# Buggy code
def __init__(self, metainfo=None, torrent_parameters=None):
    """
    Create a new TorrentDef object, possibly based on existing data.
    :param metainfo: A dictionary with metainfo, i.e. from a .torrent file.
    :param torrent_parameters: User-defined parameters for the new TorrentDef.
    """
    self._logger = logging.getLogger(self.__class__.__name__)
    self.torrent_parameters = {}
    self.metainfo = metainfo
    self.files_list = []
    self.infohash = None

    if metainfo is not None:
        # This is a workaround to avoid feeding unicode objects to Libtorrent.
        # In fact, this conforms to the 'Unicode Sandwich' model for handling unicode in Python.
        # However, it is too bad that the low-level Libtorrent wrapper does not handle unicode.
        metainfo = convert_dict_unicode_to_bytes(metainfo)

        # First, make sure the passed metainfo is valid
        try:
            lt.torrent_info(metainfo)
        except RuntimeError as exc:
            raise ValueError(str(exc))

        self.infohash = sha1(bencode(metainfo[b"info"])).digest()
        self.copy_metainfo_to_torrent_parameters()

    elif torrent_parameters:
        self.torrent_parameters.update(torrent_parameters)


# Traceback (RuntimeError)
Traceback (most recent call last):
File "TriblerGUI\core_manager.py", line 118, in on_received_state
RuntimeError: [Failure instance: Traceback: <type 'exceptions.AttributeError'>: 'unicode' object has no attribute 'items'
run_tribler.py:85:start_tribler
Tribler\Core\Session.py:438:start
lib\site-packages\twisted\internet\defer.py:321:addCallback
lib\site-packages\twisted\internet\defer.py:310:addCallbacks
--- <exception caught here> ---
lib\site-packages\twisted\internet\defer.py:653:_runCallbacks
Tribler\Core\Session.py:429:load_checkpoint
Tribler\Core\Session.py:384:load_checkpoint
Tribler\Core\APIImplementation\LaunchManyCore.py:573:load_checkpoint
Tribler\Core\APIImplementation\LaunchManyCore.py:570:do_load_checkpoint
Tribler\Core\APIImplementation\LaunchManyCore.py:602:resume_download
Tribler\Core\TorrentDef.py:133:load_from_dict
Tribler\Core\TorrentDef.py:80:__init__
Tribler\Core\TorrentDef.py:48:convert_dict_unicode_to_bytes
]

# Fixed code
def __init__(self, metainfo=None, torrent_parameters=None):
    """
    Create a new TorrentDef object, possibly based on existing data.
    :param metainfo: A dictionary with metainfo, i.e. from a .torrent file.
    :param torrent_parameters: User-defined parameters for the new TorrentDef.
    """
    self._logger = logging.getLogger(self.__class__.__name__)
    self.torrent_parameters = {}
    self.metainfo = metainfo
    self.files_list = []
    self.infohash = None

    if metainfo is not None:
        # This is a workaround to avoid feeding unicode objects to Libtorrent.
        # In fact, this conforms to the 'Unicode Sandwich' model for handling unicode in Python.
        # However, it is too bad that the low-level Libtorrent wrapper does not handle unicode.
        if isinstance(metainfo, dict):
            metainfo = convert_dict_unicode_to_bytes(metainfo)

        # First, make sure the passed metainfo is valid
        try:
            lt.torrent_info(metainfo)
        except RuntimeError as exc:
            raise ValueError(str(exc))

        self.infohash = sha1(bencode(metainfo[b"info"])).digest()
        self.copy_metainfo_to_torrent_parameters()

    elif torrent_parameters:
        self.torrent_parameters.update(torrent_parameters)