Superset cannot connect to my Sqlite database

I have a database in sqlite and followed this tutorial on how to create it. I checked, the database exists and contains values.

I entered following SQLAlchemy URI in the web interface of the superset: sqlite:///Users/me/Documents/cancellation/item/eventlog.db

and got following error:

ERROR: {"error": "Connection failed!\n\nThe error message returned
was:\n'NoneType' object has no attribute
'get_password_masked_url_from_uri'"}

I do not understand why there should be a password, if in the documentation there are not passwords specified:

http://docs.sqlalchemy.org/en/rel_1_0/core/engines.html#sqlite

Code:

sqlite_file = 'eventlog.db' # the DB file
conn = sqlite3.connect(sqlite_file) 
eventlog.to_sql('eventlog', conn, if_exists='replace', index=False)
from sqlalchemy import create_engine
>engine = create_engine('sqlite:////Users/me/Documents/cancellation/item/eventlog.db)