1-) Create a new LDAP Connector and provide all the necessary fields (including the password)
2-) Before saving (Continue button), click on the Test Connection button.
3-) If the connection is successful (don't click Continue until it is successful) click Continue.
4-) Go to the Users menu and try to search. The following error will be displayed:
5-) To fix the problem, go to the Connector, provide a password and then click Update
6-) Try to search Users again; the search will work without any problem.