In this paper, we apply three different techniques, namely, the sine–cosine method, the new extended auxiliary equation method and the modified simple equation method for constructing many new exact solutions with parameters as well as bright–dark, singular and other soliton solutions of the coupled nonlinear Schrödinger equations. The solutions of these coupled nonlinear equations are compared with the well-known results.

This comment deals with the new auxiliary equation method (Khater method) introduced by MostafaM A Khater, Aly R Seadawy and Dianchen Lu in Pramana – J. Phys. 90, 59 (2018). By simple calculation, it is shown that this method is wrong. The exact solutions obtained in this paper are also wrong. In this comment, the errors in the above paper are pointed out and modified. The right method (amended Khater method) has been introduced.