This paper presents a study of errors that occur in DNA self-assembly using synthesized tile sets for template manufacturing. It is shown that due to the reduced size, aggregates assembled by a synthesized tile set are not error-free as those assembled by maximum-sized (referred to as a trivial tile set) as well asnon-synthesized tile sets. Compared with non-synthesized tile sets, aggregates assembled using synthesized tile sets also have a higher error rate at high tile concentration, but they exhibit a lower rate at low tile concentration. In this paper, it is also shown that errors in synthesized tile sets tend to appear in clusters. This is very different from non-synthesized tile sets of non-maximum size in which growth errors are mostly random in nature. These findings are discussed and evaluated for nano manufacturing (such as for template self-assembly of a QCA circuit).