UnicodeDecodeError - Seahub won't start - on Raspberry

Hello,

Seafile Version: Community 5.1.4
OS: Raspbian 4.4.38

i am using Seafile on my Raspberry Pi 3 with Raspbian. Until now Seafile works fine, but after a reboot today, Seahub won’t startup und shows the following Error:

UnicodeDecodeError: ‘utf8’ codec can’t decode byte 0xa0 in position 108: invalid start byte

Traceback (most recent call last):
  File "/home/seafile/seafile-server-5.1.4/seahub/manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/home/seafile/seafile-server-5.1.4/seahub/thirdpart/Django-1.8.10-py2.7.egg/django/core/management/__init__.py", line 354, in execute_from_command_line
    
  File "/home/seafile/seafile-server-5.1.4/seahub/thirdpart/Django-1.8.10-py2.7.egg/django/core/management/__init__.py", line 328, in execute
    else:
  File "/home/seafile/seafile-server-5.1.4/seahub/thirdpart/Django-1.8.10-py2.7.egg/django/__init__.py", line 18, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/home/seafile/seafile-server-5.1.4/seahub/thirdpart/Django-1.8.10-py2.7.egg/django/apps/registry.py", line 108, in populate
    app_config.import_models(all_models)
  File "/home/seafile/seafile-server-5.1.4/seahub/thirdpart/Django-1.8.10-py2.7.egg/django/apps/config.py", line 198, in import_models
    self.models_module = import_module(models_module_name)
  File "/usr/lib/python2.7/importlib/__init__.py", line 37, in import_module
    __import__(name)
  File "/home/seafile/seafile-server-5.1.4/seahub/seahub/notifications/models.py", line 16, in <module>
    from seahub.base.templatetags.seahub_tags import email2nickname
  File "/home/seafile/seafile-server-5.1.4/seahub/seahub/base/templatetags/seahub_tags.py", line 140, in <module>
    'Added' : _('Added'),
  File "/home/seafile/seafile-server-5.1.4/seahub/thirdpart/Django-1.8.10-py2.7.egg/django/utils/translation/__init__.py", line 84, in ugettext
    return _trans.ugettext(message)
  File "/home/seafile/seafile-server-5.1.4/seahub/thirdpart/Django-1.8.10-py2.7.egg/django/utils/translation/trans_real.py", line 330, in ugettext
    msg_with_ctxt = "%s%s%s" % (context, CONTEXT_SEPARATOR, message)
  File "/home/seafile/seafile-server-5.1.4/seahub/thirdpart/Django-1.8.10-py2.7.egg/django/utils/translation/trans_real.py", line 307, in do_translate
    
  File "/home/seafile/seafile-server-5.1.4/seahub/thirdpart/Django-1.8.10-py2.7.egg/django/utils/translation/trans_real.py", line 209, in translation
    _translations[language] = DjangoTranslation(language)
  File "/home/seafile/seafile-server-5.1.4/seahub/thirdpart/Django-1.8.10-py2.7.egg/django/utils/translation/trans_real.py", line 117, in __init__
    self._init_translation_catalog()
  File "/home/seafile/seafile-server-5.1.4/seahub/thirdpart/Django-1.8.10-py2.7.egg/django/utils/translation/trans_real.py", line 150, in _init_translation_catalog
    translation = self._new_gnu_trans(localedir)
  File "/home/seafile/seafile-server-5.1.4/seahub/thirdpart/Django-1.8.10-py2.7.egg/django/utils/translation/trans_real.py", line 144, in _new_gnu_trans
    fallback=use_null_fallback)
  File "/usr/lib/python2.7/gettext.py", line 478, in translation
    t = _translations.setdefault(key, class_(fp))
  File "/usr/lib/python2.7/gettext.py", line 180, in __init__
    self._parse(fp)
  File "/usr/lib/python2.7/gettext.py", line 337, in _parse
    tmsg = unicode(tmsg, self._charset)
  File "/usr/lib/python2.7/encodings/utf_8.py", line 16, in decode
    return codecs.utf_8_decode(input, errors, True)
UnicodeDecodeError: 'utf8' codec can't decode byte 0xa0 in position 108: invalid start byte

I use the Init-Script from the manual, to start the Seafile-Services.