  This paper is concerned with the existence and uniqueness, and Ulam--Hyers
stabilities of solutions of nonlinear impulsive $\varphi$--Hilfer fractional
differential equations. Further, we investigate the dependence of the solution
on the initial conditions, order of derivative and the functions involved in
the equations. The outcomes are acquired in the space of weighted piecewise
continuous functions by means of fixed point theorems and the generalized
version of Gronwall inequality.
