21:21:03: [ERROR] , ModuleName: TCF (TCF command: Processes:getContext failed.)21:21:03: [ERROR] Failed to start debugging session., ModuleName: TCF (TCF command: Processes:launch failed.)
First, I had to build a JTAG adapter for the Leonardo.
Since debugging a Leonardo requires different hardware and pinout than an Uno, I expected to see some details about it in the list of how Leonardo differs, or in a tutorial, or forum post, or ... something. I can find nothing of the sort.