What happened:
When I ran the lifelong learning knowledge base run_kb.py.
It shows:
Traceback (most recent call last):
File "D:\sedna-main\lib\sedna\service\run_kb.py", line 36, in
main()
File "D:\sedna-main\lib\sedna\service\run_kb.py", line 32, in main
KBServer(host=host, http_port=int(port), save_dir=kb_dir).start()
File "D:\sedna-main\lib\sedna\service\server\knowledgeBase\server.py", line 92, in start
return self.run(self.app)
File "D:\sedna-main\lib\sedna\service\server\base.py", line 93, in run
return self.wait_stop(current=current_thread)
File "D:\sedna-main\lib\sedna\service\server\base.py", line 99, in wait_stop
if not current.isAlive():
AttributeError: 'Thread' object has no attribute 'isAlive'

It seems because I am using Python 3.9. and the Thread object attribute is changed from isAlive to is_alive