Readout protection from level 1 to 0

[fgori.1]

I've a STM32L451 uC with 1.8V of supply voltage.

I've the readout protection at level 1, but I can't go back to the 0 level. I tried with stlink and jlink ( j-link STM32 Unlock) but it doesn't work.

is there a sequence to solve the problem ?

The BOR is 0

Thank you so much

[Uwe Bonnes]

Did you try a level -adapting probe?

[fgori.1]

Thank you! I changed the supply voltage to 3.0V and it's work now.