I get this error when send a invitation email. all the email setting is correct during in email server test configuration.. When I duplicate a data base and configure email it works fine. bu this db has following error. What could be wrong?

Error:
Odoo Server Error

Traceback (most recent call last):
  File "/odoo/odoo-server/odoo/addons/base/models/ir_http.py", line 237, in _dispatch
    result = request.dispatch()
  File "/odoo/odoo-server/odoo/http.py", line 682, in dispatch
    result = self._call_function(**self.params)
  File "/odoo/odoo-server/odoo/http.py", line 358, in _call_function
    return checked_call(self.db, *args, **kwargs)
  File "/odoo/odoo-server/odoo/service/model.py", line 94, in wrapper
    return f(dbname, *args, **kwargs)
  File "/odoo/odoo-server/odoo/http.py", line 346, in checked_call
    result = self.endpoint(*a, **kw)
  File "/odoo/odoo-server/odoo/http.py", line 911, in __call__
    return self.method(*args, **kw)
  File "/odoo/odoo-server/odoo/http.py", line 530, in response_wrap
    response = f(*args, **kw)
  File "/odoo/odoo-server/addons/web/controllers/main.py", line 1363, in call_button
    action = self._call_kw(model, method, args, kwargs)
  File "/odoo/odoo-server/addons/web/controllers/main.py", line 1351, in _call_kw
    return call_kw(request.env[model], method, args, kwargs)
  File "/odoo/odoo-server/odoo/api.py", line 396, in call_kw
    result = _call_kw_multi(method, model, args, kwargs)
  File "/odoo/odoo-server/odoo/api.py", line 383, in _call_kw_multi
    result = method(recs, *args, **kwargs)
  File "/odoo/odoo-server/addons/auth_signup/models/res_users.py", line 205, in action_reset_password
    template.send_mail(user.id, force_send=force_send, raise_exception=True)
  File "/odoo/odoo-server/addons/mail/models/mail_template.py", line 288, in send_mail
    mail.send(raise_exception=raise_exception)
  File "/odoo/odoo-server/addons/mail/models/mail_mail.py", line 272, in send
    smtp_session.quit()
  File "/usr/lib/python3.8/smtplib.py", line 988, in quit
    res = self.docmd("quit")
  File "/usr/lib/python3.8/smtplib.py", line 424, in docmd
    self.putcmd(cmd, args)
  File "/usr/lib/python3.8/smtplib.py", line 371, in putcmd
    self.send(str)
  File "/usr/lib/python3.8/smtplib.py", line 363, in send
    raise SMTPServerDisconnected('please run connect() first')
Exception

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/odoo/odoo-server/odoo/http.py", line 638, in _handle_exception
    return super(JsonRequest, self)._handle_exception(exception)
  File "/odoo/odoo-server/odoo/http.py", line 314, in _handle_exception
    raise exception.with_traceback(None) from new_cause
smtplib.SMTPServerDisconnected: please run connect() first