Security errors for Kali Linux repositories when I run "sudo apt update" on Ubuntu 20.04 [duplicate]

I've been trying to run sudo apt update and I get this output that doesn't seem to actually update:

Hit:1 stable InRelease
Hit:2 stable InRelease
Hit:3 stable InRelease
Get:4 kali-rolling InRelease [30.5 kB]
Err:4 kali-rolling InRelease The following signatures couldn't be verified because the public key is not available: NO_PUBKEY ED444FF07D8D0BF6
Reading package lists... Done
W: GPG error: kali-rolling InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY ED444FF07D8D0BF6
E: The repository ' kali-rolling InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

It doesn't seem to actually update (unless it is and I just can't see it), and I don't know what's causing the issue. I'm running Ubuntu 20.04.1 LTS with AMD64 build. Does anyone have a possible theory to what this is, or even a fix?

1 Answer

I had almost this exact same problem last night. I ran sudo apt-get update and looked for any repositories that I no longer used, removed them, and everything seems to work.