- If you use esp-open-sdk, you don't need to do anything if you followed last notice of required upgrade http://forum.micropython.org/viewtopic. ... 689#p14850 . However, I'd recommend to rebuild to make sure you didn't miss earlier upgrade and get everyone on the actual 1.2.1, not pre-release.
- Otherwise, if you installed just esptool.py, upgrade using "pip install esptool"
- If you use any other flashing utility, which is not officially supported and you do this on your own risk and under self-support, please be sure to set the exact flash size of your module.
Note that auto-detection works only for standard flash sizes supported for ESP8266, i.e. up to 4Mbyte.