GPG...an unsupported filetype?

[Faradn]

SBC:    Rockpro64 v2.1 4Gb
OS:     ubuntu 18.04 minimal w / Mate' DE     
        Linux rockpro64 4.4.190-1233-rockchip-ayufan-gd3f1be0ed310 #1 SMP Wed Aug 28 08:59:34 UTC 2019 aarch64 aarch64 aarch64 GNU/Linux

While performing an apt update && apt upgrade, the following messages occur:

W: http://ppa.launchpad.net/ayufan/rock64-0.../InRelease: The key(s) in the keyring /etc/apt/trusted.gpg.d/ayufan.key.chroot.gpg are ignored as the file has an unsupported filetype.
W: http://ports.ubuntu.com/ubuntu-ports/dis.../InRelease: The key(s) in the keyring /etc/apt/trusted.gpg.d/ayufan.key.chroot.gpg are ignored as the file has an unsupported filetype.
W: http://ppa.launchpad.net/ayufan/rock64-0.../InRelease: The key(s) in the keyring /etc/apt/trusted.gpg.d/ayufan.key.chroot.gpg are ignored as the file has an unsupported filetype.
W: http://ports.ubuntu.com/ubuntu-ports/dis.../InRelease: The key(s) in the keyring /etc/apt/trusted.gpg.d/ayufan.key.chroot.gpg are ignored as the file has an unsupported filetype.
W: http://ports.ubuntu.com/ubuntu-ports/dis.../InRelease: The key(s) in the keyring /etc/apt/trusted.gpg.d/ayufan.key.chroot.gpg are ignored as the file has an unsupported filetype.
W: http://deb.ayufan.eu/orgs/ayufan-rock64/.../InRelease: The key(s) in the keyring /etc/apt/trusted.gpg.d/ayufan.key.chroot.gpg are ignored as the file has an unsupported filetype.

Any explainations? Concerns?

TIA,
/Faradn
~ Rockpro64 ~ Odroid N2 ~ Odroid XU4 ~ Pi 3B ~

[Mentaluproar]

I'm getting this too. Did you find a fix?

[nationalicon]

1) Remove the broken keyring:

Code:

sudo rm /etc/apt/trusted.gpg.d/ayufan.key.chroot.gpg

2) Try to update:

Code:

sudo apt-get update

You will receive an error "The following signatures couldn't be verified because the public key is not available: NO_PUBKEY XXXXXXXXXXXXXXXX"
(where XXXXXXXXXXXXXXXX is the public key)

3) Add missing key to keyring:

Code:

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys XXXXXXXXXXXXXXXX

(where XXXXXXXXXXXXXXXX is the public key from the error above)

4) Update again :

Code:

sudo apt-get update

This is how I solved it; but anyone more knowledgeable than me is welcome to explain in more detail, or suggest a better solution.