Flashing issue

[Carsco]

I have this problem often.
Every now and then I can flash, sometimes only with merged file.
What can I do?

Now, after several attempts, I managed to flash the merged file. Without touching anything.
What could it depend on?

[reppr]

In similar situations I have found that changing the USB cable can help.

[Carsco]

Thanks. I'll try.