# pdbedit -e smbpasswd:/root/smb-users.backup
  build_sam_pass: Failing attempt to store user with non-uid based user RID.
  smbpasswd_update_sam_account: build_smb_pass failed!
  Importing account for root...failed

source3/passdb/passdb.c
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    565 bool algorithmic_pdb_rid_is_user(uint32 rid)
    566 {
    567         if ( rid_is_well_known(rid) ) {
    568                 /*
    569                  * The only well known user RIDs are DOMAIN_USER_RID_ADMIN
    570                  * and DOMAIN_USER_RID_GUEST.
    571                  */
    572                 if(rid == DOMAIN_USER_RID_ADMIN || rid == DOMAIN_USER_RID_GUEST)
    573                         return True;
    574         } else if((rid & RID_TYPE_MASK) == USER_RID_TYPE) { 
                  /* When rid is an odd number, False is returned. */
    575                 return True;
    576         }
    577         return False;
    578 }
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