I was getting this error while compiling NuttX for an ESP32 board:

LD: nuttx
CP: nuttx.hex
MKIMAGE: ESP32 binary

esptool.py not found.  Please run: "pip install esptool"

Run make again to create the nuttx.bin image.
make: *** [tools/Unix.mk:553: nuttx] Error 1

Even after running “pip install esptool” the error still happening.

The solution that worked for me was install it as root:

$ sudo pip install esptool

• BrainDamage