  In this paper, we aim to solving the open question left in [Nie, Yuan:
Nonlinear Anal 196 (2020); J. Math. Anal. Appl 505 (2022)) and Xiao, Fei: J.
Math. Anal. Appl 514 (2022)]. We prove that a multidimensional chemotaxis
system is ill-posedness in $\dot{B}_{2d, r}^{-\frac{3}{2}}
\times\big(\dot{B}_{2d, r}^{-\frac{1}{2}}\big)^{d}$ when $1\leq r<d$ due to the
lack of continuity of the solution.
