diff --git a/cps/about.py b/cps/about.py
index ceef7308..edbdb6ab 100644
--- a/cps/about.py
+++ b/cps/about.py
@@ -68,7 +68,6 @@ _VERSIONS = OrderedDict(
     Flask_SimpleLDAP =  u'installed' if bool(services.ldap) else u'not installed',
     Goodreads = u'installed' if bool(services.goodreads_support) else u'not installed',
     jsonschema = services.SyncToken.__version__  if bool(services.SyncToken) else u'not installed',
-
 )
 _VERSIONS.update(uploader.get_versions())
 
diff --git a/cps/admin.py b/cps/admin.py
index 91ebe997..ab3d0f22 100644
--- a/cps/admin.py
+++ b/cps/admin.py
@@ -64,7 +64,6 @@ except ImportError:
     oauth_check = {}
 
 
-
 feature_support['gdrive'] = gdrive_support
 admi = Blueprint('admin', __name__)
 log = logger.create()
@@ -491,7 +490,6 @@ def _configuration_update_helper():
     db_change = False
     to_save = request.form.to_dict()
 
-    # _config_dict = lambda x: config.set_from_dictionary(to_save, x, lambda y: y['id'])
     _config_string = lambda x: config.set_from_dictionary(to_save, x, lambda y: y.strip() if y else y)
     _config_int = lambda x: config.set_from_dictionary(to_save, x, int)
     _config_checkbox = lambda x: config.set_from_dictionary(to_save, x, lambda y: y == "on", False)
@@ -531,8 +529,6 @@ def _configuration_update_helper():
     if config.config_certfile and not os.path.isfile(config.config_certfile):
         return _configuration_result('Certfile location is not valid, please enter correct path', gdriveError)
 
-    _config_string("config_server_url")
-
     _config_checkbox_int("config_uploading")
     _config_checkbox_int("config_anonbrowse")
     _config_checkbox_int("config_public_reg")
@@ -845,24 +841,6 @@ def edit_user(user_id):
                 content.default_language = to_save["default_language"]
             if "locale" in to_save and to_save["locale"]:
                 content.locale = to_save["locale"]
-
-            if "kobo_user_key" in to_save and to_save["kobo_user_key"]:
-                kobo_user_key_hash = generate_password_hash(to_save["kobo_user_key"])
-                if kobo_user_key_hash != content.kobo_user_key_hash:
-                    existing_kobo_user_key = ub.session.query(ub.User).filter(ub.User.kobo_user_key_hash == kobo_user_key_hash).first()
-                    if not existing_kobo_user_key:
-                        content.kobo_user_key_hash = kobo_user_key_hash
-                    else:
-                        flash(_(u"Found an existing account for this Kobo UserKey."), category="error")
-                        return render_title_template("user_edit.html",
-                                                     translations=translations,
-                                                     languages=languages,
-                                                     new_user=0,
-                                                     content=content,
-                                                     downloads=downloads,
-                                                     registered_oauth=oauth_check,
-                                                     feature_support=feature_support,
-                                                     title=_(u"Edit User %(nick)s", nick=content.nickname), page="edituser")
             if to_save["email"] and to_save["email"] != content.email:
                 existing_email = ub.session.query(ub.User).filter(ub.User.email == to_save["email"].lower()) \
                     .first()
diff --git a/cps/config_sql.py b/cps/config_sql.py
index 86279331..a00b4217 100644
--- a/cps/config_sql.py
+++ b/cps/config_sql.py
@@ -49,7 +49,6 @@ class _Settings(_Base):
     config_port = Column(Integer, default=constants.DEFAULT_PORT)
     config_certfile = Column(String)
     config_keyfile = Column(String)
-    config_server_url = Column(String, default='')
 
     config_calibre_web_title = Column(String, default=u'Calibre-Web')
     config_books_per_page = Column(Integer, default=60)
@@ -313,7 +312,6 @@ def _migrate_table(session, orm_class):
 
     if changed:
         session.commit()
-    session.query
 
 def autodetect_calibre_binary():
     if sys.platform == "win32":
diff --git a/cps/constants.py b/cps/constants.py
index 7630b38f..a78c31b3 100644
--- a/cps/constants.py
+++ b/cps/constants.py
@@ -106,7 +106,6 @@ except ValueError:
 del env_CALIBRE_PORT
 
 
-
 EXTENSIONS_AUDIO    = {'mp3', 'm4a', 'm4b'}
 EXTENSIONS_CONVERT  = {'pdf', 'epub', 'mobi', 'azw3', 'docx', 'rtf', 'fb2', 'lit', 'lrf', 'txt', 'htmlz', 'rtf', 'odt'}
 EXTENSIONS_UPLOAD   = {'txt', 'pdf', 'epub', 'mobi', 'azw', 'azw3', 'cbr', 'cbz', 'cbt', 'djvu', 'prc', 'doc', 'docx',
diff --git a/cps/kobo.py b/cps/kobo.py
index 73536551..7e1cbc8e 100644
--- a/cps/kobo.py
+++ b/cps/kobo.py
@@ -40,7 +40,8 @@ from werkzeug.datastructures import Headers
 from sqlalchemy import func
 import requests
 
-from . import config, logger, kobo_auth, db, helper, services
+from . import config, logger, kobo_auth, db, helper
+from .services import SyncToken as SyncToken
 from .web import download_required
 
 KOBO_FORMATS = {"KEPUB": ["KEPUB"], "EPUB": ["EPUB", "EPUB3"]}
@@ -72,6 +73,8 @@ CONNECTION_SPECIFIC_HEADERS = [
 def redirect_or_proxy_request():
     if request.method == "GET":
         return redirect(get_store_url_for_current_request(), 307)
+    if request.method == "DELETE":
+        return make_response(jsonify({}))
     else:
         # The Kobo device turns other request types into GET requests on redirects, so we instead proxy to the Kobo store ourselves.
         outgoing_headers = Headers(request.headers)
@@ -97,7 +100,7 @@ def redirect_or_proxy_request():
 @login_required
 @download_required
 def HandleSyncRequest():
-    sync_token = services.SyncToken.from_headers(request.headers)
+    sync_token = SyncToken.SyncToken.from_headers(request.headers)
     log.info("Kobo library sync request received.")
 
     # TODO: Limit the number of books return per sync call, and rely on the sync-continuatation header
@@ -117,7 +120,7 @@ def HandleSyncRequest():
     changed_entries = (
         db.session.query(db.Books)
         .join(db.Data)
-        .filter(func.datetime(db.Books.last_modified) > sync_token.books_last_modified)
+        .filter(func.datetime(db.Books.last_modified) != sync_token.books_last_modified)
         .filter(db.Data.format.in_(KOBO_FORMATS))
         .all()
     )
@@ -322,11 +325,10 @@ def reading_state(book):
     return reading_state
 
 
-@kobo.route(
-    "/<book_uuid>/image.jpg"
-)
+@kobo.route("/<book_uuid>/image.jpg")
 @login_required
 def HandleCoverImageRequest(book_uuid):
+    log.debug("Cover request received for book %s" % book_uuid)
     book_cover = helper.get_book_cover_with_uuid(
         book_uuid, use_generic_cover_on_failure=False
     )
@@ -346,7 +348,7 @@ def TopLevelEndpoint():
 @kobo.route("/v1/library/tags", methods=["POST"])
 @kobo.route("/v1/library/tags/<shelf_name>", methods=["POST"])
 @kobo.route("/v1/library/tags/<tag_id>", methods=["DELETE"])
-def HandleUnimplementedRequest(book_uuid=None, shelf_name=None, tag_id=None):
+def HandleUnimplementedRequest(dummy=None, book_uuid=None, shelf_name=None, tag_id=None):
     return redirect_or_proxy_request()
 
 
diff --git a/cps/services/SyncToken.py b/cps/services/SyncToken.py
index 2a17f7b5..21f16acc 100644
--- a/cps/services/SyncToken.py
+++ b/cps/services/SyncToken.py
@@ -42,7 +42,7 @@ def to_epoch_timestamp(datetime_object):
     return (datetime_object - datetime(1970, 1, 1)).total_seconds()
 
 
-class SyncToken:
+class SyncToken():
     """ The SyncToken is used to persist state accross requests.
     When serialized over the response headers, the Kobo device will propagate the token onto following requests to the service.
     As an example use-case, the SyncToken is used to detect books that have been added to the library since the last time the device synced to the server.
diff --git a/cps/templates/config_edit.html b/cps/templates/config_edit.html
index 2ae56a38..b0ad49f7 100644
--- a/cps/templates/config_edit.html
+++ b/cps/templates/config_edit.html
@@ -104,10 +104,6 @@
                     <!--option-- value="3" {% if config.config_updatechannel == 3 %}selected{% endif %}>{{_('Nightly (Automatic)')}}</option-->
             </select>
         </div>
-        <div class="form-group">
-          <label for="config_server_url">{{_('Server Url. This is only used for the (experimental) Kobo device library sync')}}</label>
-          <input type="text" class="form-control" name="config_server_url" id="config_server_url" value="{% if config.config_server_url != None %}{{ config.config_server_url }}{% endif %}" autocomplete="off">
-        </div>
       </div>
     </div>
   </div>
diff --git a/cps/templates/user_edit.html b/cps/templates/user_edit.html
index a044f270..9ef11979 100644
--- a/cps/templates/user_edit.html
+++ b/cps/templates/user_edit.html
@@ -27,10 +27,6 @@
       <input type="email" class="form-control" name="kindle_mail" id="kindle_mail" value="{{ content.kindle_mail if content.kindle_mail != None }}">
     </div>
     <div class="form-group">
-    <div class="form-group">
-        <label for="kobo_user_key">{{_('KoboStore UserKey')}}</label>
-        <input type="password" class="form-control" name="kobo_user_key" id="kobo_user_key" value="" autocomplete="off">
-    </div>
     <label for="locale">{{_('Language')}}</label>
         <select name="locale" id="locale" class="form-control">
             {%  for translation in translations %}
diff --git a/cps/ub.py b/cps/ub.py
index e79c62b2..8564ef21 100644
--- a/cps/ub.py
+++ b/cps/ub.py
@@ -330,7 +330,7 @@ class RemoteAuthToken(Base):
     __tablename__ = 'remote_auth_token'
 
     id = Column(Integer, primary_key=True)
-    auth_token = Column(String, unique=True)        # IMPORTANT: ToDo:check length restríction id not valid for string
+    auth_token = Column(String, unique=True)
     user_id = Column(Integer, ForeignKey('user.id'))
     verified = Column(Boolean, default=False)
     expiration = Column(DateTime)
diff --git a/cps/web.py b/cps/web.py
index 24f26953..5c535e8d 100644
--- a/cps/web.py
+++ b/cps/web.py
@@ -250,6 +250,7 @@ def edit_required(f):
 
     return inner
 
+
 # ################################### Helper functions ################################################################
 
 
@@ -460,12 +461,6 @@ def get_matching_tags():
         if len(exclude_tag_inputs) > 0:
             for tag in exclude_tag_inputs:
                 q = q.filter(not_(db.Books.tags.any(db.Tags.id == tag)))
-        '''if len(include_extension_inputs) > 0:
-            for tag in exclude_tag_inputs:
-                q = q.filter(not_(db.Books.tags.any(db.Tags.id == tag)))
-        if len(exclude_extension_inputs) > 0:
-            for tag in exclude_tag_inputs:
-                q = q.filter(not_(db.Books.tags.any(db.Tags.id == tag)))'''
         for book in q:
             for tag in book.tags:
                 if tag.id not in tag_dict['tags']:
@@ -1048,9 +1043,6 @@ def serve_book(book_id, book_format, anyname):
 @login_required_if_no_ano
 @download_required
 def download_link(book_id, book_format):
-    if book_format.lower() == "kepub":
-        book_format= "epub"
-    log.info("Book %s in format %s downloaded", str(book_id), book_format)
     return get_download_link(book_id, book_format)
 
 
@@ -1092,10 +1084,10 @@ def register():
         if not to_save["nickname"] or not to_save["email"]:
             flash(_(u"Please fill out all fields!"), category="error")
             return render_title_template('register.html', title=_(u"register"), page="register")
+
         existing_user = ub.session.query(ub.User).filter(func.lower(ub.User.nickname) == to_save["nickname"]
                                                          .lower()).first()
         existing_email = ub.session.query(ub.User).filter(ub.User.email == to_save["email"].lower()).first()
-
         if not existing_user and not existing_email:
             content = ub.User()
             # content.password = generate_password_hash(to_save["password"])