Stamp errors are often highly prized by philatelic investors and collectors. The reason stamps with printing errors are so desirable is because their defects have unintentionally created some of the rarest and most visually striking stamps in the world. With such a wide range of striking stamp errors to collect, some of which are surprisingly affordable, this area of philately is one of the fastest growing in terms of popularity A postage stamp error refers to any of several types of failures which can occur in the stamp production process, resulting in the finished product not appearing as intended. It encompasses everything from major design errors and missing parts of the design to the use of wrong colours, incorrect denominations and misplaced or inverted design elements Philatelists reserve the term ‘error’ for obvious production failures. Every part of the printing and production process is strictly controlled by the postal authorities in order to spot and address any issues before stamps go on public sale. Nevertheless, oversights happen Many different factors cause postage stamp errors – and one of the main types of error is design error. As far as Sri Lankan Postage stamps are concerned the main design stamp error was occurred in 1983. The Postal Department of Sri Lanka decided to issue series of stamps to commemorate distinguished personalities such as H. W. Amarasuriya, Father S. G. Perera, C. A. Lorenz, N. H. M. Abdul Cader and C. W. Thamotheram Pillai under the category of National Heroes on the 22 of May 1983.

Although they have printed said set of stamps, since they have used wrong portrait instead of correct portrait of Thamotheram Pillai, they withdrew it and issued only four other stamps.

Somehow the correct stamp to commemorate C. W. Thamotheram Pillai was issued on 01st
October 1983.

The Other design error in Sri Lankan Postal history was happened in 1997. The Sri Lankan Postal authority decided to issue a stamp on veteran writer, poet, artist and the lyricist Mr. Mahagamasekera. At the design stage his name was written as Gath Kathuwara Mahagamasekera (Writer Mahagamasekera) somehow it was printed on the stamp as Shantha Kumara Mahagamasekera in all three languages. Subsequently that words Shantha Kumara were hide with over print of star marks and issued.