'Error creating manual index or constraint' during site import

WARN [Long running task: Importing data] [atlassian.confluence.setup.DefaultHibernateConfigurator] doInTransaction Error creating manual index or constraint: [alter table cwd_membership add constraint cwd_unique_user_membership unique (parent_id, child_user_id), alter table cwd_user add constraint cwd_user_name_dir_id unique (lower_user_name, directory_id), alter table cwd_group add constraint cwd_group_name_dir_id unique (lower_group_name, directory_id), alter table cwd_user_attribute add constraint cwd_unique_usr_attr unique (directory_id, user_id, attribute_name, attribute_lower_value), alter table cwd_group_attribute add constraint cwd_unique_grp_attr unique (directory_id, group_id, attribute_name, attribute_lower_value), alter table cwd_membership add constraint cwd_unique_group_membership unique (parent_id, child_group_id), alter table CONTENT_PERM add constraint cp_unique_user unique (CPS_ID, CP_TYPE, USERNAME), alter table CONTENT_PERM add constraint cp_unique_group unique (CPS_ID, CP_TYPE, GROUPNAME), alter table CONTENT_PERM_SET add constraint cps_unique_type unique (CONTENT_ID, CONT_PERM_TYPE), alter table BANDANA add constraint bandana_unique_key unique (BANDANACONTEXT, BANDANAKEY)], StatementCallback; uncategorized SQLException for SQL [alter table cwd_user add constraint cwd_user_name_dir_id unique (lower_user_name, directory_id)]; SQL state [25P02]; error code [0]; ERROR: current transaction is aborted, commands ignored until end of transaction block; nested exception is org.postgresql.util.PSQLException: ERROR: current transaction is aborted, commands ignored until end of transaction block