Another option (but not without risk), you can edit the IOC file and change the mininum cubemx required version, I am pretty sure they did not change anything between 6.12.0 and 6.12.1 they just broke the tool

I believe this present under tools only for some devices. At least for a F103C8Tx it does not exist

And this prevents rolling back to previous version or CubeMX 

Well, this is not the solution either. In my case, for STM32F103C8Tx, CubeMX does not allow configuring it's memories (under tools).CubeMX produces an .ld file completely different when exporting for Makefiles and exporting with build files for STM32...