Methuselah who listen to community will long last. (Good choice not to go for Graviex.)
Your strength comes from the community~~~
Keep going~ Live Long~   

Dear Astrali

I am a novice in Linux but bought Raspberry Pi3 to run the moonlander 2.
however I got stock in running "sudo apt install libjansson-dev libcurl4-openssl-dev"
in the terminal mode, i typed (copy and pasted as well) but it say "libjansson-dev" package can not be found. nor Libcurl4-dev has no condidate to install.
  (I may not describe it exactly cause i have to translate into English. )
What do i miss in here?

Thanks in advance.

install neccesary library files (thanks to jstefanop for providing this info)