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Unable to start FUS. FUS version is and FUS_STATE_ERR_UNKNOWN


I'm trying to fix a P-Nucleo-WB55 board using CubeProgrammer.

However, the board shows a version of FUS and Stack and I cannot start FUS.

I don't know why there is no version because the FUS cannot be deleted forever in the FUS upgrade document.

So, How can I update FUS in this version?

The SBRV option byte is 0x3ffff is it common?






ST Employee

Hello @KKIM.6 

According to the SBRV value, FUS is not running. I suggest you try to update your firmware Following this wiki and using the last version (included in the version 1.18.0 of the STM32CubeWB).

Best Regards.


To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

Could you send the link again?


I'm trying to upgrade FUS following the "STM32WB Firmware Upgrade Service wiki" but there is no description when FUS does not exist.


I couldn't solve this problem yet...

ST Employee

The SBRV value is pointing on the safeboot which means something went badly wrong during the update.

I assume the SFSA value to be FFFF protecting the last sector.

Did you already program this board? 

I would be nice to get the ESE and SFSA values.


Then one thing that may work to recover your board in a manufactory state is to write the value 0x00008000 at the address 0x5800040C. This should work if ESE option byte is checked.