A definitive fix for the Flatpak installation error: runtime/org.freedesktop.Platform/x86_64/1.6 not installed.
Fix for Flatpak Installation Error
Flatpak is a new way of distributing apps in Linux ecosystem and while enabling Flatpak you may face some unwanted errors like below:
error: runtime/org.freedesktop.Platform/x86_64/1.6 not installed
If you interrupt the process while enabling Flatpak repositories due to some reasons e.g. internet connectivity lost etc, the Flatpak installation remains incomplete and may unstable your system. There is a likely chance that you may get above error while installing any Flatpak apps after you encountered above error.
If you face the above error, run the below command from the terminal and reboot the computer. This command would correct any missing packages/errors and make your system usable for Flatpak.
flatpak update -v
After reboot, try to perform the operation which you were trying to do. It would be resolved.
If this solved your error, let me know using the comment box below.