diff --git a/cps/editbooks.py b/cps/editbooks.py
index 1d61c8dd..f2ad969c 100755
--- a/cps/editbooks.py
+++ b/cps/editbooks.py
@@ -241,7 +241,7 @@ def delete_book_ajax(book_id, book_format):
 
 
 def delete_whole_book(book_id, book):
-    # delete book from Shelfs, Downloads, Read list
+    # delete book from shelves, Downloads, Read list
     ub.session.query(ub.BookShelf).filter(ub.BookShelf.book_id == book_id).delete()
     ub.session.query(ub.ReadBook).filter(ub.ReadBook.book_id == book_id).delete()
     ub.delete_download(book_id)
@@ -383,7 +383,7 @@ def render_edit_book(book_id):
     for authr in book.authors:
         author_names.append(authr.name.replace('|', ','))
 
-    # Option for showing convertbook button
+    # Option for showing convert_book button
     valid_source_formats = list()
     allowed_conversion_formats = list()
     kepub_possible = None
@@ -413,11 +413,11 @@ def render_edit_book(book_id):
 
 def edit_book_ratings(to_save, book):
     changed = False
-    if to_save.get("rating","").strip():
+    if to_save.get("rating", "").strip():
         old_rating = False
         if len(book.ratings) > 0:
             old_rating = book.ratings[0].rating
-        rating_x2 = int(float(to_save.get("rating","")) * 2)
+        rating_x2 = int(float(to_save.get("rating", "")) * 2)
         if rating_x2 != old_rating:
             changed = True
             is_rating = calibre_db.session.query(db.Ratings).filter(db.Ratings.rating == rating_x2).first()
@@ -622,8 +622,9 @@ def edit_cc_data(book_id, book, to_save, cc):
                                               'custom')
     return changed
 
+
 # returns None if no file is uploaded
-# returns False if an error occours, in all other cases the ebook metadata is returned
+# returns False if an error occurs, in all other cases the ebook metadata is returned
 def upload_single_file(file_request, book, book_id):
     # Check and handle Uploaded file
     requested_file = file_request.files.get('btn-upload-format', None)
@@ -676,7 +677,7 @@ def upload_single_file(file_request, book, book_id):
                     calibre_db.session.rollback()
                     log.error_or_exception("Database error: {}".format(e))
                     flash(_(u"Database error: %(error)s.", error=e.orig), category="error")
-                    return False # return redirect(url_for('web.show_book', book_id=book.id))
+                    return False  # return redirect(url_for('web.show_book', book_id=book.id))
 
             # Queue uploader info
             link = '<a href="{}">{}</a>'.format(url_for('web.show_book', book_id=book.id), escape(book.title))
@@ -688,6 +689,7 @@ def upload_single_file(file_request, book, book_id):
                 rarExecutable=config.config_rarfile_location)
     return None
 
+
 def upload_cover(cover_request, book):
     requested_file = cover_request.files.get('btn-upload-cover', None)
     if requested_file:
@@ -698,7 +700,7 @@ def upload_cover(cover_request, book):
                 return False
             ret, message = helper.save_cover(requested_file, book.path)
             if ret is True:
-                helper.clear_cover_thumbnail_cache(book.id)
+                helper.replace_cover_thumbnail_cache(book.id)
                 return True
             else:
                 flash(message, category="error")
@@ -739,6 +741,7 @@ def handle_author_on_edit(book, author_name, update_stored=True):
         change = True
     return input_authors, change, renamed
 
+
 @EditBook.route("/admin/book/<int:book_id>", methods=['GET'])
 @login_required_if_no_ano
 @edit_required
@@ -815,6 +818,7 @@ def edit_book(book_id):
                 if result is True:
                     book.has_cover = 1
                     modify_date = True
+                    helper.replace_cover_thumbnail_cache(book.id)
                 else:
                     flash(error, category="error")
 
@@ -986,7 +990,7 @@ def create_book_on_upload(modify_date, meta):
 
     try:
         pubdate = datetime.strptime(meta.pubdate[:10], "%Y-%m-%d")
-    except:
+    except ValueError:
         pubdate = datetime(101, 1, 1)
 
     # Calibre adds books with utc as timezone
@@ -1063,18 +1067,18 @@ def file_handling_on_upload(requested_file):
 def move_coverfile(meta, db_book):
     # move cover to final directory, including book id
     if meta.cover:
-        coverfile = meta.cover
+        cover_file = meta.cover
     else:
-        coverfile = os.path.join(constants.STATIC_DIR, 'generic_cover.jpg')
-    new_coverpath = os.path.join(config.config_calibre_dir, db_book.path)
+        cover_file = os.path.join(constants.STATIC_DIR, 'generic_cover.jpg')
+    new_cover_path = os.path.join(config.config_calibre_dir, db_book.path)
     try:
-        os.makedirs(new_coverpath, exist_ok=True)
-        copyfile(coverfile, os.path.join(new_coverpath, "cover.jpg"))
+        os.makedirs(new_cover_path, exist_ok=True)
+        copyfile(cover_file, os.path.join(new_cover_path, "cover.jpg"))
         if meta.cover:
             os.unlink(meta.cover)
     except OSError as e:
-        log.error("Failed to move cover file %s: %s", new_coverpath, e)
-        flash(_(u"Failed to Move Cover File %(file)s: %(error)s", file=new_coverpath,
+        log.error("Failed to move cover file %s: %s", new_cover_path, e)
+        flash(_(u"Failed to Move Cover File %(file)s: %(error)s", file=new_cover_path,
                 error=e),
               category="error")
 
@@ -1193,7 +1197,7 @@ def edit_list_book(param):
     vals = request.form.to_dict()
     book = calibre_db.get_book(vals['pk'])
     sort_param = ""
-    # ret = ""
+    ret = ""
     try:
         if param == 'series_index':
             edit_book_series_index(vals['value'], book)
diff --git a/cps/helper.py b/cps/helper.py
index 43b7141d..ea5820dd 100644
--- a/cps/helper.py
+++ b/cps/helper.py
@@ -820,9 +820,6 @@ def save_cover_from_url(url, book_path):
             log.error("python modul advocate is not installed but is needed")
             return False, _("Python modul 'advocate' is not installed but is needed for cover downloads")
         img.raise_for_status()
-        #            # cover_processing()
-            # move_coverfile(meta, db_book)
-
         return save_cover(img, book_path)
     except (socket.gaierror,
             requests.exceptions.HTTPError,
@@ -1020,7 +1017,7 @@ def render_task_status(tasklist):
             ret['user'] = escape(user)  # prevent xss
 
             # Hidden fields
-            ret['id'] = task.id
+            ret['task_id'] = task.id
             ret['stat'] = task.stat
             ret['is_cancellable'] = task.is_cancellable
 
@@ -1078,8 +1075,12 @@ def get_download_link(book_id, book_format, client):
 
 
 def clear_cover_thumbnail_cache(book_id):
-    WorkerThread.add(None, TaskClearCoverThumbnailCache(book_id, _("Replace Thumbnail for book {}".format(book_id))),
-                     hidden=True)
+    WorkerThread.add(None, TaskClearCoverThumbnailCache(book_id), hidden=True)
+
+
+def replace_cover_thumbnail_cache(book_id):
+    WorkerThread.add(None, TaskClearCoverThumbnailCache(book_id), hidden=True)
+    WorkerThread.add(None, TaskGenerateCoverThumbnails(book_id), hidden=True)
 
 
 def delete_thumbnail_cache():
diff --git a/cps/kobo.py b/cps/kobo.py
index f2a3b2f8..46e68acb 100644
--- a/cps/kobo.py
+++ b/cps/kobo.py
@@ -148,8 +148,8 @@ def HandleSyncRequest():
         sync_token.books_last_created = datetime.datetime.min
         sync_token.reading_state_last_modified = datetime.datetime.min
 
-    new_books_last_modified = sync_token.books_last_modified # needed for sync selected shelfs only
-    new_books_last_created = sync_token.books_last_created # needed to distinguish between new and changed entitlement
+    new_books_last_modified = sync_token.books_last_modified  # needed for sync selected shelfs only
+    new_books_last_created = sync_token.books_last_created  # needed to distinguish between new and changed entitlement
     new_reading_state_last_modified = sync_token.reading_state_last_modified
 
     new_archived_last_modified = datetime.datetime.min
@@ -176,18 +176,17 @@ def HandleSyncRequest():
                            .join(db.Data).outerjoin(ub.ArchivedBook, and_(db.Books.id == ub.ArchivedBook.book_id,
                                                                           ub.ArchivedBook.user_id == current_user.id))
                            .filter(db.Books.id.notin_(calibre_db.session.query(ub.KoboSyncedBooks.book_id)
-                                           .filter(ub.KoboSyncedBooks.user_id == current_user.id)))
-                .filter(ub.BookShelf.date_added > sync_token.books_last_modified)
-                .filter(db.Data.format.in_(KOBO_FORMATS))
-                .filter(calibre_db.common_filters(allow_show_archived=True))
-                .order_by(db.Books.id)
-                .order_by(ub.ArchivedBook.last_modified)
-                .join(ub.BookShelf, db.Books.id == ub.BookShelf.book_id)
-                .join(ub.Shelf)
-                .filter(ub.Shelf.user_id == current_user.id)
-                .filter(ub.Shelf.kobo_sync)
-                .distinct()
-        )
+                                                      .filter(ub.KoboSyncedBooks.user_id == current_user.id)))
+                           .filter(ub.BookShelf.date_added > sync_token.books_last_modified)
+                           .filter(db.Data.format.in_(KOBO_FORMATS))
+                           .filter(calibre_db.common_filters(allow_show_archived=True))
+                           .order_by(db.Books.id)
+                           .order_by(ub.ArchivedBook.last_modified)
+                           .join(ub.BookShelf, db.Books.id == ub.BookShelf.book_id)
+                           .join(ub.Shelf)
+                           .filter(ub.Shelf.user_id == current_user.id)
+                           .filter(ub.Shelf.kobo_sync)
+                           .distinct())
     else:
         if sqlalchemy_version2:
             changed_entries = select(db.Books, ub.ArchivedBook.last_modified, ub.ArchivedBook.is_archived)
@@ -196,16 +195,14 @@ def HandleSyncRequest():
                                                        ub.ArchivedBook.last_modified,
                                                        ub.ArchivedBook.is_archived)
         changed_entries = (changed_entries
-                   .join(db.Data).outerjoin(ub.ArchivedBook, and_(db.Books.id == ub.ArchivedBook.book_id,
-                                                                  ub.ArchivedBook.user_id == current_user.id))
-                   .filter(db.Books.id.notin_(calibre_db.session.query(ub.KoboSyncedBooks.book_id)
-                                              .filter(ub.KoboSyncedBooks.user_id == current_user.id)))
-                   .filter(calibre_db.common_filters(allow_show_archived=True))
-                   .filter(db.Data.format.in_(KOBO_FORMATS))
-                   .order_by(db.Books.last_modified)
-                   .order_by(db.Books.id)
-        )
-
+                           .join(db.Data).outerjoin(ub.ArchivedBook, and_(db.Books.id == ub.ArchivedBook.book_id,
+                                                                          ub.ArchivedBook.user_id == current_user.id))
+                           .filter(db.Books.id.notin_(calibre_db.session.query(ub.KoboSyncedBooks.book_id)
+                                                      .filter(ub.KoboSyncedBooks.user_id == current_user.id)))
+                           .filter(calibre_db.common_filters(allow_show_archived=True))
+                           .filter(db.Data.format.in_(KOBO_FORMATS))
+                           .order_by(db.Books.last_modified)
+                           .order_by(db.Books.id))
 
     reading_states_in_new_entitlements = []
     if sqlalchemy_version2:
@@ -215,7 +212,7 @@ def HandleSyncRequest():
     log.debug("Books to Sync: {}".format(len(books.all())))
     for book in books:
         formats = [data.format for data in book.Books.data]
-        if not 'KEPUB' in formats and config.config_kepubifypath and 'EPUB' in formats:
+        if 'KEPUB' not in formats and config.config_kepubifypath and 'EPUB' in formats:
             helper.convert_book_format(book.Books.id, config.config_calibre_dir, 'EPUB', 'KEPUB', current_user.name)
 
         kobo_reading_state = get_or_create_reading_state(book.Books.id)
@@ -262,7 +259,7 @@ def HandleSyncRequest():
             .columns(db.Books).first()
     else:
         max_change = changed_entries.from_self().filter(ub.ArchivedBook.is_archived)\
-            .filter(ub.ArchivedBook.user_id==current_user.id) \
+            .filter(ub.ArchivedBook.user_id == current_user.id) \
             .order_by(func.datetime(ub.ArchivedBook.last_modified).desc()).first()
 
     max_change = max_change.last_modified if max_change else new_archived_last_modified
@@ -425,9 +422,9 @@ def get_author(book):
     author_list = []
     autor_roles = []
     for author in book.authors:
-        autor_roles.append({"Name":author.name})    #.encode('unicode-escape').decode('latin-1')
+        autor_roles.append({"Name": author.name})
         author_list.append(author.name)
-    return {"ContributorRoles": autor_roles, "Contributors":author_list}
+    return {"ContributorRoles": autor_roles, "Contributors": author_list}
 
 
 def get_publisher(book):
@@ -441,6 +438,7 @@ def get_series(book):
         return None
     return book.series[0].name
 
+
 def get_seriesindex(book):
     return book.series_index or 1
 
@@ -485,7 +483,7 @@ def get_metadata(book):
         "Language": "en",
         "PhoneticPronunciations": {},
         "PublicationDate": convert_to_kobo_timestamp_string(book.pubdate),
-        "Publisher": {"Imprint": "", "Name": get_publisher(book),},
+        "Publisher": {"Imprint": "", "Name": get_publisher(book), },
         "RevisionId": book_uuid,
         "Title": book.title,
         "WorkId": book_uuid,
@@ -504,6 +502,7 @@ def get_metadata(book):
 
     return metadata
 
+
 @csrf.exempt
 @kobo.route("/v1/library/tags", methods=["POST", "DELETE"])
 @requires_kobo_auth
@@ -718,7 +717,6 @@ def sync_shelves(sync_token, sync_results, only_kobo_shelves=False):
             *extra_filters
         ).distinct().order_by(func.datetime(ub.Shelf.last_modified).asc())
 
-
     for shelf in shelflist:
         if not shelf_lib.check_shelf_view_permissions(shelf):
             continue
@@ -764,6 +762,7 @@ def create_kobo_tag(shelf):
         )
     return {"Tag": tag}
 
+
 @csrf.exempt
 @kobo.route("/v1/library/<book_uuid>/state", methods=["GET", "PUT"])
 @requires_kobo_auth
@@ -808,7 +807,7 @@ def HandleStateRequest(book_uuid):
                 book_read = kobo_reading_state.book_read_link
                 new_book_read_status = get_ub_read_status(request_status_info["Status"])
                 if new_book_read_status == ub.ReadBook.STATUS_IN_PROGRESS \
-                    and new_book_read_status != book_read.read_status:
+                        and new_book_read_status != book_read.read_status:
                     book_read.times_started_reading += 1
                     book_read.last_time_started_reading = datetime.datetime.utcnow()
                 book_read.read_status = new_book_read_status
@@ -848,7 +847,7 @@ def get_ub_read_status(kobo_read_status):
 
 def get_or_create_reading_state(book_id):
     book_read = ub.session.query(ub.ReadBook).filter(ub.ReadBook.book_id == book_id,
-                                                          ub.ReadBook.user_id == int(current_user.id)).one_or_none()
+                                                     ub.ReadBook.user_id == int(current_user.id)).one_or_none()
     if not book_read:
         book_read = ub.ReadBook(user_id=current_user.id, book_id=book_id)
     if not book_read.kobo_reading_state:
@@ -912,6 +911,7 @@ def get_current_bookmark_response(current_bookmark):
         }
     return resp
 
+
 @kobo.route("/<book_uuid>/<width>/<height>/<isGreyscale>/image.jpg", defaults={'Quality': ""})
 @kobo.route("/<book_uuid>/<width>/<height>/<Quality>/<isGreyscale>/image.jpg")
 @requires_kobo_auth
@@ -989,8 +989,8 @@ def handle_getests():
     if config.config_kobo_proxy:
         return redirect_or_proxy_request()
     else:
-        testkey = request.headers.get("X-Kobo-userkey","")
-        return make_response(jsonify({"Result": "Success", "TestKey":testkey, "Tests": {}}))
+        testkey = request.headers.get("X-Kobo-userkey", "")
+        return make_response(jsonify({"Result": "Success", "TestKey": testkey, "Tests": {}}))
 
 
 @csrf.exempt
@@ -1020,7 +1020,7 @@ def make_calibre_web_auth_response():
     content = request.get_json()
     AccessToken = base64.b64encode(os.urandom(24)).decode('utf-8')
     RefreshToken = base64.b64encode(os.urandom(24)).decode('utf-8')
-    return  make_response(
+    return make_response(
         jsonify(
             {
                 "AccessToken": AccessToken,
@@ -1158,14 +1158,16 @@ def NATIVE_KOBO_RESOURCES():
         "eula_page": "https://www.kobo.com/termsofuse?style=onestore",
         "exchange_auth": "https://storeapi.kobo.com/v1/auth/exchange",
         "external_book": "https://storeapi.kobo.com/v1/products/books/external/{Ids}",
-        "facebook_sso_page": "https://authorize.kobo.com/signin/provider/Facebook/login?returnUrl=http://store.kobobooks.com/",
+        "facebook_sso_page":
+            "https://authorize.kobo.com/signin/provider/Facebook/login?returnUrl=http://store.kobobooks.com/",
         "featured_list": "https://storeapi.kobo.com/v1/products/featured/{FeaturedListId}",
         "featured_lists": "https://storeapi.kobo.com/v1/products/featured",
         "free_books_page": {
             "EN": "https://www.kobo.com/{region}/{language}/p/free-ebooks",
             "FR": "https://www.kobo.com/{region}/{language}/p/livres-gratuits",
             "IT": "https://www.kobo.com/{region}/{language}/p/libri-gratuiti",
-            "NL": "https://www.kobo.com/{region}/{language}/List/bekijk-het-overzicht-van-gratis-ebooks/QpkkVWnUw8sxmgjSlCbJRg",
+            "NL": "https://www.kobo.com/{region}/{language}/"
+                  "List/bekijk-het-overzicht-van-gratis-ebooks/QpkkVWnUw8sxmgjSlCbJRg",
             "PT": "https://www.kobo.com/{region}/{language}/p/livros-gratis",
         },
         "fte_feedback": "https://storeapi.kobo.com/v1/products/ftefeedback",
@@ -1190,7 +1192,8 @@ def NATIVE_KOBO_RESOURCES():
         "library_stack": "https://storeapi.kobo.com/v1/user/library/stacks/{LibraryItemId}",
         "library_sync": "https://storeapi.kobo.com/v1/library/sync",
         "love_dashboard_page": "https://store.kobobooks.com/{culture}/kobosuperpoints",
-        "love_points_redemption_page": "https://store.kobobooks.com/{culture}/KoboSuperPointsRedemption?productId={ProductId}",
+        "love_points_redemption_page":
+            "https://store.kobobooks.com/{culture}/KoboSuperPointsRedemption?productId={ProductId}",
         "magazine_landing_page": "https://store.kobobooks.com/emagazines",
         "notifications_registration_issue": "https://storeapi.kobo.com/v1/notifications/registration",
         "oauth_host": "https://oauth.kobo.com",
@@ -1206,7 +1209,8 @@ def NATIVE_KOBO_RESOURCES():
         "product_recommendations": "https://storeapi.kobo.com/v1/products/{ProductId}/recommendations",
         "product_reviews": "https://storeapi.kobo.com/v1/products/{ProductIds}/reviews",
         "products": "https://storeapi.kobo.com/v1/products",
-        "provider_external_sign_in_page": "https://authorize.kobo.com/ExternalSignIn/{providerName}?returnUrl=http://store.kobobooks.com/",
+        "provider_external_sign_in_page":
+            "https://authorize.kobo.com/ExternalSignIn/{providerName}?returnUrl=http://store.kobobooks.com/",
         "purchase_buy": "https://www.kobo.com/checkout/createpurchase/",
         "purchase_buy_templated": "https://www.kobo.com/{culture}/checkout/createpurchase/{ProductId}",
         "quickbuy_checkout": "https://storeapi.kobo.com/v1/store/quickbuy/{PurchaseId}/checkout",
diff --git a/cps/schedule.py b/cps/schedule.py
index 79e0006c..5500f1a9 100644
--- a/cps/schedule.py
+++ b/cps/schedule.py
@@ -45,7 +45,7 @@ def get_scheduled_tasks(reconnect=True):
 
 def end_scheduled_tasks():
     worker = WorkerThread.get_instance()
-    for __, __, __, task in worker.tasks:
+    for __, __, __, task, __ in worker.tasks:
         if task.scheduled and task.is_cancellable:
             worker.end_task(task.id)
 
diff --git a/cps/services/worker.py b/cps/services/worker.py
index c1a8c384..63d83bfb 100644
--- a/cps/services/worker.py
+++ b/cps/services/worker.py
@@ -156,7 +156,7 @@ class WorkerThread(threading.Thread):
 
     def end_task(self, task_id):
         ins = self.get_instance()
-        for __, __, __, task in ins.tasks:
+        for __, __, __, task, __ in ins.tasks:
             if str(task.id) == str(task_id) and task.is_cancellable:
                 task.stat = STAT_CANCELLED if task.stat == STAT_WAITING else STAT_ENDED
 
diff --git a/cps/static/js/table.js b/cps/static/js/table.js
index bb38fc9f..47c3b70e 100644
--- a/cps/static/js/table.js
+++ b/cps/static/js/table.js
@@ -641,9 +641,9 @@ function UserActions (value, row) {
 /* Function for cancelling tasks */
 function TaskActions (value, row) {
     var cancellableStats = [0, 1, 2];
-    if (row.id && row.is_cancellable && cancellableStats.includes(row.stat)) {
+    if (row.task_id && row.is_cancellable && cancellableStats.includes(row.stat)) {
         return [
-            "<div class=\"task-cancel\" data-toggle=\"modal\" data-target=\"#cancelTaskModal\" data-task-id=\"" + row.id + "\" title=\"Cancel\">",
+            "<div class=\"task-cancel\" data-toggle=\"modal\" data-target=\"#cancelTaskModal\" data-task-id=\"" + row.task_id + "\" title=\"Cancel\">",
             "<i class=\"glyphicon glyphicon-ban-circle\"></i>",
             "</div>"
         ].join("");
diff --git a/cps/tasks/thumbnail.py b/cps/tasks/thumbnail.py
index c66c30ec..d11ef50c 100644
--- a/cps/tasks/thumbnail.py
+++ b/cps/tasks/thumbnail.py
@@ -50,7 +50,7 @@ def get_best_fit(width, height, image_width, image_height):
     resize_height = int(height / 2.0)
     aspect_ratio = image_width / image_height
 
-    # If this image's aspect ratio is different than the first image, then resize this image
+    # If this image's aspect ratio is different from the first image, then resize this image
     # to fill the width and height of the first image
     if aspect_ratio < width / height:
         resize_width = int(width / 2.0)
@@ -225,7 +225,7 @@ class TaskGenerateCoverThumbnails(CalibreTask):
 
     def __str__(self):
         if self.book_id > 0:
-            return "Add Thumbnail for book {}".format(self.book_id)
+            return "Add Cover Thumbnails for Book {}".format(self.book_id)
         else:
             return "Generate Cover Thumbnails"
 
@@ -501,7 +501,7 @@ class TaskClearCoverThumbnailCache(CalibreTask):
     # needed for logging
     def __str__(self):
         if self.book_id > 0:
-            return "Replace Thumbnail cache for book " + str(self.book_id)
+            return "Replace/Delete Cover Thumbnails for book " + str(self.book_id)
         else:
             return "Delete Thumbnail cache directory"
 
diff --git a/optional-requirements.txt b/optional-requirements.txt
index fea410e5..07e1ad88 100644
--- a/optional-requirements.txt
+++ b/optional-requirements.txt
@@ -1,5 +1,5 @@
 # GDrive Integration
-google-api-python-client>=1.7.11,<2.44.0
+google-api-python-client>=1.7.11,<2.46.0
 gevent>20.6.0,<22.0.0
 greenlet>=0.4.17,<1.2.0
 httplib2>=0.9.2,<0.21.0
@@ -13,7 +13,7 @@ rsa>=3.4.2,<4.9.0
 
 # Gmail
 google-auth-oauthlib>=0.4.3,<0.6.0
-google-api-python-client>=1.7.11,<2.44.0
+google-api-python-client>=1.7.11,<2.46.0
 
 # goodreads
 goodreads>=0.3.2,<0.4.0