Fixing Flatpak public key error

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…


This returns something that looks similar to this…

--2022-02-01 17:16:26--
Resolving (,, 2a00:1098:82:e::1:1, ...
Connecting to (||: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 
-rw-rw-r-- 1 garf garf 2844 Feb 1 17:37 

That’s it! No more Flatpak public key error. You should now be able to install Flatpak applications to your home directory as intended. 🙂


Related Images:

2 thoughts on “Fixing Flatpak public key error

  1. 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!

Leave a Reply

Your email address will not be published. Required fields are marked *


Please enter the CAPTCHA text