diff --git a/aprendizations/initdb.py b/aprendizations/initdb.py
index 14c4fb9..e5e9883 100644
--- a/aprendizations/initdb.py
+++ b/aprendizations/initdb.py
@@ -84,25 +84,24 @@ def get_students_from_csv(filename):
         'skipinitialspace': True,
         }
 
+    students = []
     try:
         with open(filename, encoding='iso-8859-1') as file:
             csvreader = csv.DictReader(file, **csv_settings)
             students = [{
                 'uid': s['N.º'],
                 'name': capwords(re.sub(r'\(.*\)', '', s['Nome']).strip())
-            } for s in csvreader]
+                } for s in csvreader]
     except OSError:
         print(f'!!! Error reading file "{filename}" !!!')
-        students = []
     except csv.Error:
         print(f'!!! Error parsing CSV from "{filename}" !!!')
-        students = []
 
     return students
 
 
 # ===========================================================================
-def show_students_in_database(session, verbose=False):
+def show_students_in_database(session, verbose=False) -> None:
     '''shows students in the database'''
     users = session.execute(select(Student)).scalars().all()
     total = len(users)
@@ -136,7 +135,7 @@ def main():
     Base.metadata.create_all(engine)  # Creates schema if needed
     session = Session(engine, future=True)
 
-    # --- build list of students to insert/update
+    # --- make list of students to insert/update
     students = []
 
     for csvfile in args.csvfile:
@@ -145,24 +144,22 @@ def main():
     if args.admin:
         students.append({'uid': '0', 'name': 'Admin'})
 
-    if args.add:
+    if args.add is not None:
         for uid, name in args.add:
             students.append({'uid': uid, 'name': name})
 
     # --- only insert students that are not yet in the database
     print('\nInserting new students:')
+    db_students = session.execute(select(Student.id)).scalars().all()
+    new_students = [s for s in students if s['uid'] not in set(db_students)]
+    for student in new_students:
+        print(f'  {student["uid"]}, {student["name"]}')
 
-    db_students = set(session.execute(select(Student.id)).scalars().all())
-    new_students = (s for s in students if s['uid'] not in db_students)
-    count = 0
-    for s in new_students:
-        print(f'  {s["uid"]}, {s["name"]}')
-
-        pw = args.pw or s['uid']
-        hashed_pw = bcrypt.hashpw(pw.encode('utf-8'), bcrypt.gensalt())
-
-        session.add(Student(id=s['uid'], name=s['name'], password=hashed_pw))
-        count += 1
+        passwd = args.pw or student['uid']
+        hashed_pw = bcrypt.hashpw(passwd.encode('utf-8'), bcrypt.gensalt())
+        session.add(Student(id=student['uid'],
+                            name=student['name'],
+                            password=hashed_pw))
 
     try:
         session.commit()
@@ -170,23 +167,24 @@ def main():
         print('!!! Integrity error. Aborted !!!\n')
         session.rollback()
     else:
-        print(f'Total {count} new student(s).')
+        print(f'Total {len(new_students)} new student(s).')
 
-    # --- update data for student in the database
+    # --- update data for students in the database
     if args.update:
         print('\nUpdating passwords of students:')
         count = 0
         for sid in args.update:
             try:
-                s = session.execute(select(Student).filter_by(id=sid)).scalar_one()
+                query = select(Student).filter_by(id=sid)
+                student = session.execute(query).scalar_one()
             except NoResultFound:
                 print(f'  -> student {sid} does not exist!')
                 continue
-            else:
-                print(f'  {sid}, {s.name}')
-                count += 1
-            pw = args.pw or sid
-            s.password = bcrypt.hashpw(pw.encode('utf-8'), bcrypt.gensalt())
+            count += 1
+            print(f'  {sid}, {student.name}')
+            passwd = (args.pw or sid).encode('utf-8')
+            student.password = bcrypt.hashpw(passwd, bcrypt.gensalt())
+
         session.commit()
         print(f'Total {count} password(s) updated.')
 
diff --git a/aprendizations/learnapp.py b/aprendizations/learnapp.py
index 5c3e410..89a1187 100644
--- a/aprendizations/learnapp.py
+++ b/aprendizations/learnapp.py
@@ -66,11 +66,11 @@ class LearnApp():
     def __init__(self,
                  courses: str,  # filename with course configurations
                  prefix: str,   # path to topics
-                 db: str,       # database filename
+                 dbase: str,    # database filename
                  check: bool = False) -> None:
 
-        self._db_setup(db)       # setup database and check students
-        self.online: Dict[str, Dict] = dict()    # online students
+        self._db_setup(dbase)       # setup database and check students
+        self.online: Dict[str, Dict] = {}    # online students
 
         try:
             config: Dict[str, Any] = load_yaml(courses)
@@ -91,7 +91,6 @@ class LearnApp():
         # load other course files with the topics the their deps
         for course_file in config.get('topics_from', []):
             course_conf = load_yaml(course_file)    # course configuration
-            # FIXME set defaults??
             logger.info('%6d topics from %s',
                         len(course_conf["topics"]), course_file)
             self._populate_graph(course_conf)
@@ -129,10 +128,10 @@ class LearnApp():
         logger.info('Starting sanity checks (may take a while...)')
 
         errors: int = 0
-        for qref in self.factory:
+        for qref, qfactory in self.factory.items():
             logger.debug('checking %s...', qref)
             try:
-                question = self.factory[qref].generate()
+                question = qfactory.generate()
             except QuestionException as exc:
                 logger.error(exc)
                 errors += 1
@@ -334,9 +333,6 @@ class LearnApp():
         '''Start new topic'''
 
         student = self.online[uid]['state']
-        # if uid == '0':
-        #     logger.warning('Reloading "%s"', topic)  # FIXME should be an option
-        #     self.factory.update(self._factory_for(topic))
 
         try:
             await student.start_topic(topic)
@@ -420,7 +416,7 @@ class LearnApp():
 
             topic = self.deps.nodes[tref]  # get current topic node
             topic['name'] = attr.get('name', tref)
-            topic['questions'] = attr.get('questions', [])  # FIXME unused??
+            topic['questions'] = attr.get('questions', [])
 
             for k, default in defaults.items():
                 topic[k] = attr.get(k, default)
@@ -440,7 +436,7 @@ class LearnApp():
         '''
 
         logger.info('Building questions factory:')
-        factory = dict()
+        factory = {}
         for tref in self.deps.nodes:
             factory.update(self._factory_for(tref))
 
@@ -451,7 +447,7 @@ class LearnApp():
     # makes factory for a single topic
     # ------------------------------------------------------------------------
     def _factory_for(self, tref: str) -> Dict[str, QFactory]:
-        factory: Dict[str, QFactory] = dict()
+        factory: Dict[str, QFactory] = {}
         topic = self.deps.nodes[tref]  # get node
         # load questions as list of dicts
         try:
@@ -509,7 +505,7 @@ class LearnApp():
         return factory
 
     def get_login_counter(self, uid: str) -> int:
-        '''login counter''' # FIXME
+        '''login counter'''
         return int(self.online[uid]['counter'])
 
     def get_student_name(self, uid: str) -> str:
@@ -602,14 +598,16 @@ class LearnApp():
             student_topics = session.execute(query_student_topics).all()
 
         # compute topic progress
-        now = datetime.now()
-        goals = self.courses[cid]['goals']
         progress: DefaultDict[str, float] = defaultdict(int)
+        goals = self.courses[cid]['goals']
+        num_goals = len(goals)
+        now = datetime.now()
 
         for student, topic, level, datestr in student_topics:
             if topic in goals:
                 date = datetime.strptime(datestr, "%Y-%m-%d %H:%M:%S.%f")
-                progress[student] += level**(now - date).days / len(goals)
+                elapsed_days = (now - date).days
+                progress[student] += level**elapsed_days / num_goals
 
         return sorted(((u, name, progress[u])
                        for u, name in students
diff --git a/aprendizations/main.py b/aprendizations/main.py
index fe9c1e1..14e9514 100644
--- a/aprendizations/main.py
+++ b/aprendizations/main.py
@@ -182,7 +182,7 @@ def main():
     try:
         learnapp = LearnApp(courses=arg.courses,
                             prefix=arg.prefix,
-                            db=arg.db,
+                            dbase=arg.db,
                             check=arg.check)
     except DatabaseUnusableError:
         logging.critical('Failed to start application.')
@@ -197,10 +197,7 @@ def main():
               sep='\n')
         sys.exit(1)
     except LearnException as exc:
-        logging.critical('Failed to start backend')
-        sys.exit(1)
-    except Exception:
-        logging.critical('Unknown error')
+        logging.critical('Failed to start backend: %s', str(exc))
         sys.exit(1)
     else:
         logging.info('LearnApp started')
diff --git a/aprendizations/serve.py b/aprendizations/serve.py
index 5c878c1..4d32973 100644
--- a/aprendizations/serve.py
+++ b/aprendizations/serve.py
@@ -4,10 +4,9 @@ Webserver
 
 
 # python standard library
-import asyncio
 import base64
 import functools
-import logging
+from logging import getLogger
 import mimetypes
 from os.path import join, dirname, expanduser
 import signal
@@ -28,7 +27,7 @@ from aprendizations import APP_NAME
 
 
 # setup logger for this module
-logger = logging.getLogger(__name__)
+logger = getLogger(__name__)
 
 
 # ----------------------------------------------------------------------------
@@ -37,7 +36,7 @@ def admin_only(func):
     Decorator used to restrict access to the administrator
     '''
     @functools.wraps(func)
-    def wrapper(self, *args, **kwargs):
+    def wrapper(self, *args, **kwargs) -> None:
         if self.current_user != '0':
             raise tornado.web.HTTPError(403)  # forbidden
         func(self, *args, **kwargs)
@@ -49,7 +48,7 @@ class WebApplication(tornado.web.Application):
     '''
     WebApplication - Tornado Web Server
     '''
-    def __init__(self, learnapp, debug=False):
+    def __init__(self, learnapp, debug=False) -> None:
         handlers = [
             (r'/login', LoginHandler),
             (r'/logout', LogoutHandler),
@@ -94,7 +93,6 @@ class BaseHandler(tornado.web.RequestHandler):
         counter_cookie = self.get_secure_cookie('counter')
         if user_cookie is not None:
             uid = user_cookie.decode('utf-8')
-
             if counter_cookie is not None:
                 counter = counter_cookie.decode('utf-8')
                 if counter == str(self.learn.get_login_counter(uid)):
@@ -108,7 +106,7 @@ class RankingsHandler(BaseHandler):
     Handles rankings page
     '''
     @tornado.web.authenticated
-    def get(self):
+    def get(self) -> None:
         '''
         Renders list of students that have answers in this course.
         '''
@@ -122,18 +120,17 @@ class RankingsHandler(BaseHandler):
                     name=self.learn.get_student_name(uid),
                     rankings=rankings,
                     course_id=course_id,
-                    course_title=self.learn.get_student_course_title(uid),  # FIXME get from course var
+                    course_title=self.learn.get_student_course_title(uid),
+                    # FIXME get from course var
                     )
 
 
 # ----------------------------------------------------------------------------
-#
-# ----------------------------------------------------------------------------
 class LoginHandler(BaseHandler):
     '''
     Handles /login
     '''
-    def get(self):
+    def get(self) -> None:
         '''
         Renders login page
         '''
@@ -168,7 +165,7 @@ class LogoutHandler(BaseHandler):
     Handles /logout
     '''
     @tornado.web.authenticated
-    def get(self):
+    def get(self) -> None:
         '''
         clears cookies and removes user session
         '''
@@ -176,7 +173,7 @@ class LogoutHandler(BaseHandler):
         self.clear_cookie('counter')
         self.redirect('/')
 
-    def on_finish(self):
+    def on_finish(self) -> None:
         self.learn.logout(self.current_user)
 
 
@@ -186,7 +183,7 @@ class ChangePasswordHandler(BaseHandler):
     Handles password change
     '''
     @tornado.web.authenticated
-    async def post(self):
+    async def post(self) -> None:
         '''
         Tries to perform password change and then replies success/fail status
         '''
@@ -216,7 +213,7 @@ class RootHandler(BaseHandler):
     Handles root /
     '''
     @tornado.web.authenticated
-    def get(self):
+    def get(self) -> None:
         '''Simply redirects to the main entrypoint'''
         self.redirect('/courses')
 
@@ -226,11 +223,11 @@ class CoursesHandler(BaseHandler):
     '''
     Handles /courses
     '''
-    def set_default_headers(self, *args, **kwargs):
+    def set_default_headers(self, *_) -> None:
         self.set_header('Cache-Control', 'no-cache')
 
     @tornado.web.authenticated
-    def get(self):
+    def get(self) -> None:
         '''Renders list of available courses'''
         uid = self.current_user
         self.render('courses.html',
@@ -249,7 +246,7 @@ class CourseHandler(BaseHandler):
     '''
 
     @tornado.web.authenticated
-    def get(self, course_id):
+    def get(self, course_id) -> None:
         '''
         Handles get /course/...
         Starts a given course and show list of topics
@@ -278,11 +275,11 @@ class TopicHandler(BaseHandler):
     '''
     Handles a topic
     '''
-    def set_default_headers(self, *args, **kwargs):
+    def set_default_headers(self, *_) -> None:
         self.set_header('Cache-Control', 'no-cache')
 
     @tornado.web.authenticated
-    async def get(self, topic):
+    async def get(self, topic) -> None:
         '''
         Handles get /topic/...
         Starts a given topic
@@ -308,7 +305,7 @@ class FileHandler(BaseHandler):
     Serves files from the /public subdir of the topics.
     '''
     @tornado.web.authenticated
-    async def get(self, filename):
+    async def get(self, filename) -> None:
         '''
         Serves files from /public subdirectories of a particular topic
         '''
@@ -351,7 +348,7 @@ class QuestionHandler(BaseHandler):
 
     # ------------------------------------------------------------------------
     @tornado.web.authenticated
-    async def get(self):
+    async def get(self) -> None:
         '''
         Gets question to render.
         Shows an animated trophy if there are no more questions in the topic.
@@ -489,7 +486,7 @@ def signal_handler(*_) -> None:
     reply = input(' --> Stop webserver? (yes/no) ')
     if reply.lower() == 'yes':
         tornado.ioloop.IOLoop.current().stop()
-        logging.critical('Webserver stopped.')
+        logger.critical('Webserver stopped.')
         sys.exit(0)
 
 
@@ -503,10 +500,9 @@ def run_webserver(app, ssl, port: int = 8443, debug: bool = False) -> None:
     try:
         webapp = WebApplication(app, debug=debug)
     except Exception:
-        logger.critical('Failed to start web application.')
+        logger.critical('Failed to start web application.', exc_info=True)
         sys.exit(1)
-    else:
-        logger.info('Web application started (tornado.web.Application)')
+    logger.info('Web application started (tornado.web.Application)')
 
     # --- create tornado webserver
     try:
@@ -514,19 +510,17 @@ def run_webserver(app, ssl, port: int = 8443, debug: bool = False) -> None:
     except ValueError:
         logger.critical('Certificates cert.pem and privkey.pem not found')
         sys.exit(1)
-    else:
-        logger.debug('HTTP server started')
+    logger.debug('HTTP server started')
 
     try:
         httpserver.listen(port)
     except OSError:
         logger.critical('Cannot bind port %d. Already in use?', port)
         sys.exit(1)
-
-    # --- run webserver
     logger.info('Webserver listening on %d...  (Ctrl-C to stop)', port)
     signal.signal(signal.SIGINT, signal_handler)
 
+    # --- run webserver
     try:
         tornado.ioloop.IOLoop.current().start()  # running...
     except Exception:
diff --git a/setup.py b/setup.py
index 2e0245d..17f2b63 100644
--- a/setup.py
+++ b/setup.py
@@ -18,7 +18,7 @@ setup(
     url="https://git.xdi.uevora.pt/mjsb/aprendizations.git",
     packages=find_packages(),
     include_package_data=True,   # install files from MANIFEST.in
-    python_requires='>=3.8.*',
+    python_requires='>=3.9.*',
     install_requires=[
         'tornado>=6.0',
         'mistune<2',
--
libgit2 0.21.2