Resolved! Which is the BOOT1 pin in STM32L0? Don't find in the pin description.
According to the ST boot mode selection (page 236), we can activate the bootloader following the pattern: Boot0(pin) = 1 and Boot1(pin) = 0; but the DatasheetSTM32L0 doesn’t specify which one is the BOOT1 pin in the pin description (page 33). I could...