I have a preset and I tried to use it like: mach try --present whatever That is, I misspelled "preset" as "present". mach try says: Platforms must be specified as an argument to autotry. At first I assumed this was just a bug (because mach try starts with that warning about being under development); it took a while to see the typo. It would be nicer if mach try mentioned what went wrong. E.g., take `ls' for an example: pokyo. ls --jjjjjj ls: unrecognized option '--jjjjjj' Try 'ls --help' for more information.