I believe I am getting this when I try to run ldap_connection.unbind_s()... or any variant of unbind. I think it might be because the connection is not established and I try to unbind. My version is python-ldap==3.1.0.

If that is the case then I find it a bit of an unhelpful error message. Much more helpful would be to say "cannot unbind if not bound" or something.

You know actually thing is I am able bind to ldap and search in it, but as you said, when i'm trying to use any variant of unbind that error occurs.

The error does mean "cannot unbind if not bound", and a pull request to make the message nicer would be appreciated.

I can't reproduce the unbind_s function giving that error message, though. Could you run a minimal reproducer with PYTHON_LDAP_TRACE_LEVEL=1 and PYTHON_LDAP_TRACE_FILE=somefile.log, and paste the file here (with private information removed)?

We are facing the same issue in some of our customer environments, it might be related to threading.
https://forge.univention.org/bugzilla/show_bug.cgi?id=43274

We are facing the same issue in some of our customer environments, it might be related to threading. https://forge.univention.org/bugzilla/show_bug.cgi?id=43274

Actually that UCS bug is different as it relates to ReconnectLDAPObject, while this GitHub issue here is for SimpleLDAPObject:
This SimplaLDAPOBject issue here is simple to trigger by calling unbind_s() first and then any other function as it does an del self._l:

import ldap
l = ldap.initialize("")
l.unbind_s()
l.unbind_s()

results in

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3/dist-packages/ldap/ldapobject.py", line 907, in unbind_s
    return self.unbind_ext_s(None,None)
  File "/usr/lib/python3/dist-packages/ldap/ldapobject.py", line 891, in unbind_ext_s
    msgid = self.unbind_ext(serverctrls,clientctrls)
  File "/usr/lib/python3/dist-packages/ldap/ldapobject.py", line 883, in unbind_ext
    res = self._ldap_call(self._l.unbind_ext,RequestControlTuples(serverctrls),RequestControlTuples(clientctrls))
  File "/usr/lib/python3/dist-packages/ldap/ldapobject.py", line 353, in __getattr__
    raise AttributeError('%s has no attribute %s' % (
AttributeError: SimpleLDAPObject has no attribute '_l'