Solved
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 only find the BOOT0 pin.

