Does anyone know what this error message means?

Hi

Does anyone know what this error message means?

Traceback (most recent call last):

            File “PiToArduino.py”, line 16, in <module>

                        Bus.write_byte(addr, 0x1)

OSError:         [Error 121] Remote I/O error

I am repeating Bill’s experiment to hook up a Raspberry pi to an Arduino and test it by switching the LED on and off. This was working perfectly as a test before installing the two boards into my project.

I opened the Python program in the terminal and got the prompt as bellow, so far so good.

Enter 1 for ON or 0 for OFF

I entered 1 and hit enter.

>>>>   1

I got this error.

Traceback (most recent call last):

            File “PiToArduino.py”, line 16, in <module>

                        Bus.write_byte(addr, 0x1)

OSError:         [Error 121] Remote I/O error

I’m a bit stuck because both the programs for the Arduino and Raspberry Pi 3b worked before and have not been edited since.

I’ve double-checked the code, which is exactly the same as Bill’s experiment.

I’ve double-checked the wiring, which is correct.

I2C is still enabled.

Power is getting from the Raspberry to the Arduino.

I’ve reloaded the Arduino program

All with the same result. So I’m wondering if anyone knows what this error means so I can troubleshoot the correct problem.

Thanks

Bill21