Flash programming erase step marking few sectors write protection

[KSing.4]

I am having an issue with the firmware update on STM32F427 MCU by using the ST-Link utility tool and Keil debugging functionality. When I reload the new program on MCU, sporadically flash erase step marking few sectors are write-protected. I used the Option Bytes option to unselect all->Apply command, but the command threw an internal command error.

I tried with ST_Link command utility also, it does not help

ST-LINK_CLI.exe -ME

STM32 ST-LINK CLI v3.6.0.0

STM32 ST-LINK Command Line Interface

ST-LINK SN: 39FF6E064D42343842212543

ST-LINK Firmware version: V2J29S7

Connected via SWD.

SWD Frequency = 4000K.

Target voltage = 1.9 V

Connection mode: Normal

Reset mode: Hardware reset

Device ID: 0x419

Device flash Size: 2048 Kbytes

Device family: STM32F42xxx/F43xxx

Full chip erase...

Internal command error

Read out protection is activated

ST-LINK_CLI.exe -c HOTPLUG -OB RDP=1

[TDK]

You can try using STM32CubeProgrammer instead.

If option bytes are getting set to random values, perhaps delve into when/why that's happening in the first place and correct. It is not normal behavior.

[KSing.4]

Thanks for the response, indeed the cube programmer application is able to reset the write-protected flag. I observed this flag resetting issue when I use the Keil debugger, whereas if I use the command line flash erase and reprogramming the MMU does not create any issue. Have you come across any issues with the Keil debugger before?