WIN10 ->NANO: avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0xf6

When I try to upload the firmware_V1.2b or any other sketch from my Win10-system to the UNO
I get this message:
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0xf6

Connecting the USB-cable the yellow LED blinks a few times.
The red LED lights und the blue LED blinks.
I tried 3 different USB ports at my computer and two different USB-cables.

What`s to do? Kind regards Yogibaer

Did it work before?

If you're on board manager 1.6.21 or newer, try the 'old bootloader' option in the processor menu for clones and original Nanos from before 2018.

If you're using an original Nano, produced in 2018 and are on an older board manager version, you will have to upgrade to board manager 1.6.21 (or newer but there seem to be some issues 1.6.22) and use the '328P' option in the processor menu.

Note:
board manager V1.6.21 is the first one to have the 'old bootloader' option; that's how you can recognise it.

Thanks a lot!!! Asimple click to know where and it works.