STM32H750B-DK TouchGFX Project: "Cannot access memory at address 0x90000000" During Debug
Board: STM32H750B-DK (DK32H750B$AT1)
IDE: STM32CubeIDE 1.14.1
CubeMX: 6.11.1
TouchGFX: 4.23.1
Firmware: STM32Cube FW_H7 V1.12.1
Problem Description:
I created a new TouchGFX project for the STM32H750B-DK board. The project builds successfully (0 errors, 1 warning), but I cannot debug it. When starting a debug session, I get the error: "Cannot access memory at address 0x90000000".
The project is configured to use external QSPI flash (0x90000000) for code execution (XIP) since the code size (424KB) exceeds the H750's internal flash (128KB).
What Works:
Project builds successfully
Simple non-TouchGFX blinky projects debug successfully
What Fails:
Debug session fails with memory access errors at 0x90000000
Attempts to set SP/PC from external flash vector table fail

As found
STMicroelectronics ST-LINK GDB server. Version 7.12.0
Copyright (c) 2025, STMicroelectronics. All rights reserved.
Starting server with the following options:
Persistent Mode : Disabled
Logging Level : 1
Listen Port Number : 61234
Status Refresh Delay : 15s
Verbose Mode : Disabled
SWD Debug : Enabled
InitWhile : Enabled
Waiting for debugger connection...
Debugger connected
Waiting for debugger connection...
Debugger connected
Waiting for debugger connection...
-------------------------------------------------------------------
STM32CubeProgrammer v2.21.0
-------------------------------------------------------------------
Log output file: C:\Users\asus\AppData\Local\Temp\STM32CubeProgrammer_a20920.log
ST-LINK SN : 004D00213137510C33333639
ST-LINK FW : V3J16M9
Board : STM32H750B-DK
Voltage : 3.28V
SWD freq : 8000 KHz
Connect mode: Under Reset
Reset mode : Hardware reset
Device ID : 0x450
Revision ID : Rev V
Device name : STM32H7xx
Flash size : 128 KBytes
Device type : MCU
Device CPU : Cortex-M7
BL Version : 0x90
Opening and parsing file: ST-LINK_GDB_server_a20920.srec
Memory Programming ...
File : ST-LINK_GDB_server_a20920.srec
Size : 437.95 KB
Address : 0x90000000
Erasing memory corresponding to segment 0:
Erasing external memory sectors [0 1]
Erasing memory corresponding to segment 1:
Erasing external memory sectors [16 17]
Download in Progress:
File download complete
Time elapsed during download operation: 00:00:02.260
Verifying...
Time elapsed during verifying operation: 00:00:01.786
Download verified successfully

Any guidance on proper debug configuration for external flash execution would be greatly appreciated!
NOTE: Shouldn'e external loader be found, where?
