For some time a few of our newcomers apps were not building due to an issue with Builder and Flatpak.
Finally the issues are fixed, in Flatpak 0.9.10 and in Builder stable (that you will have from Flatpak if you followed the Newcomers tutorial). Only thing needed is to update Builder and make sure Flatpak is at version 0.9.10.
If your distribution has already latest Flatpak (e.g. Fedora 26 or newer) and GNOME Software 3.24 (e.g. Fedora 26 or newer) you simply need to go Software, click the refresh icon, wait to download updates and then click “Update all”.
If you want to do it in the command line:
flatpak update flatpak update --user
And to update Flatpak in Fedora
sudo dnf update -y
Apologies for having broken builds of Newcomers apps, we definitely need a way to ensure Builder integration with apps are tested regularly in the future!
Feel free to report if something is not working as expected in our newcomers channel.
Remember you can start contributing to GNOME apps and technologies in a few minutes following our newcomers guide, give it a look!