nest upgrade fails with Invalid command on a v11 project because the global CLI hands control to the project's local @nestjs/cli 11.
Bump @nestjs/cli and @nestjs/schematics to 12 inside the project, and run the CLI on Node 24.15 or another supported version.
The tool changed seven items in our dry run but left Terminus, tsconfig, the webpack file, Jest and Lambda packaging for you.