ESP8266 Community Forum

I'm posting this for anyone that may experience this exception. I'm using an ESP12-E.
On reboot my ESP sat in a loop at 78800 reporting the following:

Fatal exception (0):
epc1=0x40100003, epc2=0x00000000, epc3=0x00000000, excvaddr=0x00000000, depc=0x00000000

I finally discovered it was because I had GPIO2 pulled low during boot (I had a switch connected to the GPIO).
It appears GPIO2 must be high or this exception occurs.

Hope this helps someone.

At least make sure all of GPIO0, GPIO2 and GPIO15 are never directly wired to either Vcc or ground. I think that's was the root cause here. Use either pull up or pull down resistors.

Hi, this is my first time ever writing something like this but after a day of struggling, I wish I knew what I did now about this dumb error. I have no idea how this error occurred but my esp-01s (1Mbyte) was stuck in this boot loop after transferring it from my pic18f45k22 to my Arduino UNO (I might have connected it wrong or something). I fixed it by using the esptool to flash the Boantong AT firmware (https://docs.ai-thinker.com/en/esp8266/sdk) to the module and instantly the boot loop/error was gone and I could interface with it effortlessly from the Arduino serial monitor. I am not sure that the GPI02 pin had anything to do with it, the module worked well on another project with the pic18 with no pull-up but I connected it to 3.3V with a 10k pull-up resistor just for safety.

Hope it helps!