Hello @Sam_ECU,
The .elf file, which the debugger is trying to write into the MCU Flash memory is not selected in the C/C++ Application field of the below configuration. This is why you get the following error:
mariuslucianand_1-1649619570968.png
mariuslucianand_0-1649619413909.png
The debugger configuration can be automatically created when the code is imported by following the below procedure:
mariuslucianand_2-1649620179722.png
mariuslucianand_3-1649620258316.png
Now, after you have built the project, in the associated Debug configuration, you will see that under the C/C++ Application, the resulted .elf file of the Build process will be selected there.
mariuslucianand_4-1649620435088.png
If the .elf is still missing, you shall Build the project, go to Debug Configuration, and press the "Search Project" button. Select the .elf file, and the debugger shall be able to flash your binary file.
mariuslucianand_5-1649620640156.png
Hope this helps,
Marius