I am very grateful of your response. I am experienced in PIC microcontrollers, on Arduino not that much. Everything I ever proggramed was on Windows, not Linux. Now I thought I could also code in Linux… but not yet works.
I will try to somemething today with this problem.
Sorry, but I don’t yet know what QEMU is. I will read about it.
I didnt’t install qemu myself. If Ubuntu distribution contains, qemu, then I have it
Still don’t knoqw what is qemi (some virtualisation…)
sudo apt-get purge qemu-user-static
then I deleted /home/darek/.Arduino folder
and then I installed qemi once again:
sudo apt-get install qemu-user-static
but in none of this step Adruino IDE worked. Just the .Arduino folder was recreated
Edit once again!!!
I just typed “arduino” in terminal. Terminal said: “arduino is not installed, you can install it with: sudo apt install arduino.” The arduino was previously installed, I have this nice icon on desktop. When double click on this icon, Arduino IDE opens, but gives that error with compilation. The error I describen in first post.
But if I type “arduino” in empty terminal, Arduino IDE launches and works properly. It is A micracle I guess.
I don’t know how to check it, but I guess it made me another, separate arduino installation. So I have now two Arduino installations: first not compiling, and the second that is able to compile.
I like Linux, but when something works here, I don’t know why…