Cannot Connect to STM32H533 After Debug Authentication (Access Port Error)

[elby0]

I’m working with a NUCLEO-H533RE board (STM32H5 series, TrustZone enabled) and using ST-LINK for debugging.

Here is the issue:

• Debug Authentication succeeds (certificate-based).
• Immediately after, the tool disconnects and shows:

Error: Unable to get core ID
Error: Cannot connect to access port 1! If you are trying to connect to a device with TrustZone enabled please try to connect with HotPlug mode. If you are trying to connect to a device which supports Debug Authentication with certificate and password, please open your device using it.

• Log shows:

SDMAuthenticate: Authentication successful
Debug Authentication Success
Disconnected from device.
ST-LINK FW: V3J16M8
Board: NUCLEO-H533RE
Voltage: 3.28V

• ST-Link configuration:
  • Port: SWD
  • Mode: HotPlug
  • Access Port: 0
  • Reset Mode: Software Reset
  • SWD Frequency: 8000 kHz
  • Shared: Disabled

I've tried:

• HotPlug Mode as recommended for TrustZone.
• Debug Authentication with valid certificate and key.
• ST-Link firmware is up to date.

Still, after authentication, I cannot connect to the core or AP.

Questions:

1. Why does the session drop immediately after authentication?
2. Is this related to TrustZone or Option Bytes (Debug permissions)?
3. Should I use “Connect under reset” instead of HotPlug?
4. Which Access Port (AP0 vs AP1) should I select for STM32H533?

Any guidance or known working configuration for STM32H5 with Debug Authentication would be appreciated!

[Imen.D]

Hello @elby0 

Welcome to the Community.

Maybe this post could be helpful to you: stm32h533 production state closed firmware not running.

Implementing debug authentication on STM32H5 using CLI tools