The classic equation for decomposing the wavefront aberrations of axis-symmetrical optical systems has the form W(h₀,ρ,Φ)=ΣΣΣC(2j+m)(2p+m)m.(h₀)Λ(2j+m). (ρ)Λ(2p+m).(cosΦ)Λm, where j, p and m are non-negative integers, ρ and Φ are the polar coordinates of the pupil, and h₀ is the object height. However, one non-zero component of the primary aberrations (i.e., C133h₀ρ³(cosΦ)³) is missing from this equation when the image plane is not the Gaussian image plane. This implies that the equation is a sufficient condition only, rather than a necessary and sufficient condition, since it cannot guarantee that all of the components of the aberrations can be found. Accordingly, this letter presents a new method for determining all the components of aberrations of any order. The results show that three and five components of the secondary and tertiary aberrations, respectively, are missing in the existing literature.