I use Linux and I was trying to use fastboot to run a command to flash the partition table on my Moto e (2015).
Whenever I did it, all I'd see was the words:
no permissions fastboot
Well, it didn't take long to find out from askubuntu.com that I just had to type 'sudo' in front of my command.
So, of course, instead of just running 'fastboot', I instead ran...
... followed by whatever options there were for the command. Really simple.