Unable to open database of udgerdb_v3.dat

[EswarRB]

from udger import Udger
import os.path
def ua_parse(user_agent):
    filepath = os.path.abspath('./udger-updater-linux/udgerdb_v3.dat')
    udger = Udger(filepath)
    result = udger.parse_ua(user_agent)
    return result
ua = 'Mozilla/5.0 (iPad; CPU OS 7_0 like Mac OS X) AppleWebKit/537.51.1 (KHTML, like Gecko) Version/7.0 Mobile/11A465 Safari/9537.53'
ua_parse(ua)

---------------------------------------------------------------------------
OperationalError                         
Traceback (most recent call last)
Cell In[15], line 9
      7     return result.user_agent.popularity_index >= 50
      8 ua = 'Mozilla/5.0 (iPad; CPU OS 7_0 like Mac OS X) AppleWebKit/537.51.1 (KHTML, like Gecko) Version/7.0 Mobile/11A465 Safari/9537.53'
----> 9 is_popular_ua(ua)

Cell In[15], line 6, in is_popular_ua(user_agent)
      4 filepath = os.path.abspath('udgerdb_v3.dat')
      5 udger = Udger(filepath)
----> 6 result = udger.parse_ua(user_agent)
      7 return result.user_agent.popularity_index >= 50

File ~./udger/parser.py:14, in Udger.parse_ua(self, ua_string)
     11     if cached is not None:
     12         return cached
---> 14 ua, class_id, client_id = self._client_detector(ua_string)
     15 is_crawler = (ua['ua_class'] == 'Crawler')
     17 opsys = self._os_detector(ua_string, client_id) if not is_crawler else None

File ~./udger/parser.py:87, in Udger._client_detector(self, ua_string)
     86 def _client_detector(self, ua_string):
---> 87     ua = self.db_get_first_row(Queries.crawler_sql, ua_string)
     88     if ua:
     89         del ua['class_id']

File ~./udger/base.py:221, in UdgerBase.db_get_first_row(self, sql, *params)
    218     def db_get_first_row(self, sql, *params):
    219 #        self.last_regexp_match = None
--> 221         self.db_cursor.execute(sql, params)
    223         for row in self.db_cursor:
    224             return row

File ~./udger/base.py:36, in cached_property.__get__(self, instance, unused_type)
     34 if instance is None:
     35     return self
---> 36 res = instance.__dict__[self.func.__name__] = self.func(instance)
     37 return res

File ~./udger/base.py:142, in UdgerBase.db_cursor(self)
    139     @cached_property
    140     def db_cursor(self):
    141         db_filepath = os.path.join(self.data_dir, self.db_filename)
--> 142         db = sqlite3.connect(db_filepath)
    143 #        db.create_function("REGEXP", 2, self.regexp_func)
    145         cursor = db.cursor()

OperationalError: unable to open database file 

Why is this happening and what can be the possible fix for this?