I had a pretty grim time recently trying to fix a “Flatpak public key error” on Ubuntu 20.04 LTS. Well KDE Neon to be more precise, but it’s underlying operating system is Ubuntu. I had been attempting a “user” mode installation of an application via Flatpak with no success. I installed Flatpak in the normal way. I opened a standard UNIX terminal application e.g. Konsole and typed…
sudo apt install flatpak
This appeared to install perfectly. I could install applications at a “system” level without problem. However, when I attempted to install at a user level, I kept getting “GPG errors”. For example, when I ran the following command in a terminal window…
flatpak install Fourier --user
It returned the following error message…
"An error was encountered searching remote ‘flathub’ for ‘Fourier’: Unable to load summary from remote flathub: Signature made Tue 01 Feb 2022 17:09:41 using RSA key ID 562702E9E3ED7EE8 Can't check signature: public key not found"
After lots of internet searches and abortive attempts to resolve this, I discovered the problem. Basically, I did not actually have flatpak’s public GPG key. Fortunately the solution is trivially easy.
First you need to download flatpak’s public key file…
wget https://flathub.org/repo/flathub.gpg
This returns something that looks similar to this…
--2022-02-01 17:16:26-- https://flathub.org/repo/flathub.gpg Resolving flathub.org (flathub.org)... 46.235.231.150, 46.235.230.111, 2a00:1098:82:e::1:1, ... Connecting to flathub.org (flathub.org)|46.235.231.150|:443... connected. HTTP request sent, awaiting response... 200 OK Length: 2844 (2.8K) [application/octet-stream] Saving to: ‘flathub.gpg’ flathub.gpg 100%[=====================================================>] 2.78K --.-KB/s in 0s 2022-02-01 17:16:26 (457 MB/s) - ‘flathub.gpg’ saved [2844/2844]
Copy and rename the key to correct location(s). If you intend to use flatpak’s “beta” repository then you need to copy a keyfile for that too.
cp flathub.gpg ~/.local/share/flatpak/repo/flathub.trustedkeys.gpg cp flathub.gpg ~/.local/share/flatpak/repo/flathub-beta.trustedkeys.gpg
Make sure the keyfiles are actually where they should be…
ls -la ~/.local/share/flatpak/repo/*.trustedkeys.gpg
Should return something similar to this…
-rw-rw-r-- 1 garf garf 2844 Feb 1 17:41 /home/garf/.local/share/flatpak/repo/flathub-beta.trustedkeys.gpg -rw-rw-r-- 1 garf garf 2844 Feb 1 17:37 /home/garf/.local/share/flatpak/repo/flathub.trustedkeys.gpg
That’s it! No more Flatpak public key error. You should now be able to install Flatpak applications to your home directory as intended. 🙂
I installed some apps with one user, but when trying to install apps on other user I was getting this same issue, super weird.
Anyways, I was able to fix it using your suggestion, thank you!
Excellent. Glad to be of service. 🙂