I just completed a new uSD card with the latest Buster image; all of the updates and the changes necessary to run my apps. All of the apps work fine, except for a Console app that continiously polls remote device through the UART, ttyAMA0 (hardware serial port on GPIO 14 and 15).
On a RPi3, everything runs perfectly without any issue.
However when the same uSD card is used on an RPi4(either 2 or 4gig) when this app is started, a few seconds later the Pi shuts down. There are no logs either - unless I am looking in the wrong place.
Any idea why it would work in a Pi3 and not a Pi4?