I had this error using STM32CubeProgrammer, and no combination of software versions fixed it.

What fixed it for me, was to set an external loader for my board. Click on the "EL" button in the left column of STM32CubeProgrammer and you will see a list of loaders for various boards, which hopefully includes yours.

I see that the OP already configured an external loader, so his problem looks to be different, but if you are searching that error then you will find this post like I did.

I have an STM32H745I-DISCO and have been trying to build and load the demonstration application that comes preloaded with that board. It tries to load into location 0x90000000 and beyond, which is external QSPI flash. STM32CubeProgrammer can't program external flash without an external loader.

(The only reason I'm using STM32CubeProgrammer is that I could not get STM32CubeIDE to program my board. This toolset has been no end of headaches for me.)