Duplicate LDAP Index

These errors occur when an LDAP Add attempts to set a duplicate value on an indexed (unique) attribute. The underlying error returned by LDAP is:
LDAP_ALREADY_EXISTS (68)

Search the log file for Duplicate LDAP Index to identify the record(s) that are throwing this error. Unfortunately, the error returned by LDAP does not identify the attribute for which a duplication has occurred. Common attributes that throw this error are UID, userid, proxyaddresses, samaccountname, mail, alias etc. Any attribute that is required to be unique will throw this error if an LDAP Add attempts to set a duplicate value.

To identify exactly which attribute is throwing the error, use a custom object map file to comment out suspect attributes one at a time. A mapping can be commented out by placing a # as the first character in the line, like this:
#mail#64=~mail~

After commenting out a mapping, run the Sync. If the error disappears, you have identified the problem attribute. The data for that attribute must then be modified at the Source for the records throwing that error.