App command doesn't exist

So after building project with base: core20 snapcraft can’t find the app command. I’ve checked in snapcraft --debug mode that executable “server” exists for sure, and it has path starting from the root of the lxd container: parts/myapp/build/build/programs/server . I’m trying this:

    apps:
        server:
            command: parts/myapp/build/build/programs/server

And it returns:

Failed to generate snap metadata: The specified command 'parts/myapp/build/build/programs/server' defined in the app 'server' does not exist.
Ensure that 'parts/myapp/build/build/programs/server' is installed with the correct path.

What I should enter to the command part of the snapcraft.yaml?

you need to define your command: relative to the prime directory, not the parts directory … i.e. if a part has built and installed something into prime/usr/bin/foo you add

command: usr/bin/foo