Why do I get ADMINLIMIT_EXCEEDED: {'desc': 'Administrative limit exceeded'} ?

Issue

I'm getting the following traces on keystone.log

2018-05-01 19:34:47.562 399410 ERROR keystone.common.wsgi   File "/usr/lib64/python2.7/site-packages/ldap/ldapobject.py", line 469, in result3
2018-05-01 19:34:47.562 399410 ERROR keystone.common.wsgi     resp_ctrl_classes=resp_ctrl_classes
2018-05-01 19:34:47.562 399410 ERROR keystone.common.wsgi   File "/usr/lib64/python2.7/site-packages/ldap/ldapobject.py", line 476, in result4
2018-05-01 19:34:47.562 399410 ERROR keystone.common.wsgi     ldap_result = self._ldap_call(self._l.result4,msgid,all,timeout,add_ctrls,add_intermediates,add_extop)
2018-05-01 19:34:47.562 399410 ERROR keystone.common.wsgi   File "/usr/lib64/python2.7/site-packages/ldap/ldapobject.py", line 99, in _ldap_call
2018-05-01 19:34:47.562 399410 ERROR keystone.common.wsgi     result = func(*args,**kwargs)
2018-05-01 19:34:47.562 399410 ERROR keystone.common.wsgi ADMINLIMIT_EXCEEDED: {'desc': 'Administrative limit exceeded'}