I was getting this error and a NameNotFoundException exception thrown in PortalLDAPUtil::_importGroupsAndMembershipFromLDAPUser . The group DN that was shown in the exception was gotten from the LDAP entry for the user logging in, reflected in their groupMembership attribute. Doing an ldapsearch from the command line confirmed this. I could not figure out why I was getting the exception however, since the group certainly does exist. I changed the user's LDAP settings to be a member of another, known, working group and got the same exception. Odd.

My fix was to change the ldap.import.method property in portal-ext.properties from user to group. The exception complaining about the group DN went away, though now I have a different exception.

Excerpted portal-ext.properties below:

#ldap.import.method=user
ldap.import.method=group