Hi,
thanks for the link. The links in the thread are dead so it wasn't directly helpful. I got some new words for a google research but it wasn't helping as well.
Even an empty sketch like
void setup() {
// put your setup code here, to run once:
}
void loop() {
// put your main code here, to run repeatedly:
}
cannot be compiled. The error message is the same as I get for my sketch.
Wishes & happy new year