Authentication through LDAP was working and not it has stopped working. You can go to the OneClick Administration Page -> Debugging -> Web Server Debug Page (Runtime) page and enable the following debug options:
Single Sign-On Integration
SSORB Security SP
Once you have reproduced the issue, please check the <SPECROOT>/tomcat/logs/stdout.log (Windows) or <SPECROOT>/tomcat/logs/catalina.out (Linux) for the following error:
Connection Exception: javax.naming.AuthenticationException: [LDAP: error code 49 - 80090308: LdapErr: DSID-0C09042A, comment: AcceptSecurityContext error, data 52e, v3839�]
Connection problem: javax.naming.CommunicationException: SPC-OCA-10494: Could not connect with the specified connection name/password: SPC-OCA-10488: Either the user name does not exist in the external authentication database or the entered password is Invalid.
The issue is with the user authentication from the LDAP server. Please have your local LDAP team look into the issue.
For reference, you can also use the link below for other LDAP codes: