hashcracking a WPA2 8 char caps [need support]

hi everyone,

This is probally the most noobquestion ever but i couldnt get a right instruction video on how to do this.
so i finally managed to build  a hccp from a .cap file using aircrack-ng -J

now i want to go try randomizing chars in caps on my hccp file but im kinda stuck in the menu
i think im close but i dont know so i hope someone can help me out.

i want to randomize 8 characters all captions for instance HGYUIOPN
so my command line is as follows.
 # | Device Type
 ===+=============
  1 | CPU
  2 | GPU
  3 | FPGA, DSP, Co-Processor



hashcat -m 2500 3 /root/Desktop/8.hccap ?u?u?u?u?u?u?u?u
hashcat (v3.10) starting...



ERROR: 3: No such file or directory

file exist tho


so im stuck now.