gpg: no valid OpenPGP data found.

[edurenye]

Distribution:

Ubuntu 20.10

Issue/Bug Description:

I was trying to build my own ISO from Pop-os 21.04, I generated my own GPG key and uploaded it to the keyserver.
I added the key id to GPG_NAME in the Makefile, tried to run make, but I got the following error:

+ dpkg --add-architecture i386
+ '[' -n /iso/pop.key ']'
+ echo 'Adding APT key: /iso/pop.key'
Adding APT key: /iso/pop.key
+ apt-key add /iso/pop.key
Warning: apt-key is deprecated. Manage keyring files in trusted.gpg.d instead (see apt-key(8)).
gpg: no valid OpenPGP data found.
make: *** [mk/chroot.mk:53: build/pop-os/21.04/chroot] Error 2