I am unable to perform software updates on my new Ubuntu 22.04 installation due to the following error/issue:
Warning: GPG error: https://deb.opera.com/opera-stable stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY XX3C36XXXDE1B7XX
Error: The repository 'https://deb.opera.com/opera-stable stable InRelease' is not signed.
I have attempted various solutions from checking online but nothing seems to solve this issue.
UPDATE
I tried this answer provided in the suggested duplicate How do I fix the GPG error "NO_PUBKEY"?. The first method didn't work and then I tried the ALTERNATE METHOD and here are the results from that:
> sudo gpg --keyserver pgpkeys.mit.edu --recv-key XX3C36XXXDE1B7XX
gpg: directory '/root/.gnupg' created
gpg: keybox '/root/.gnupg/pubring.kbx' created
gpg: /root/.gnupg/trustdb.gpg: trustdb created
gpg: key XX3C36XXXDE1B7XX: public key "Opera Software Archive Automatic Signing Key 2021 <packager@opera.com>" imported
gpg: Total number processed: 1
gpg: imported: 1
> sudo gpg -a --export XX3C36XXXDE1B7XX | sudo apt-key add -
Warning: apt-key is deprecated. Manage keyring files in trusted.gpg.d instead (see apt-key(8)).
OK
> sudo apt-get update
Get:10 https://deb.opera.com/opera-stable stable InRelease [2,590 B]
Err:10 https://deb.opera.com/opera-stable stable InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY XX3C36XXXDE1B7XX
W: GPG error: https://deb.opera.com/opera-stable stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY DD3C368A8DE1B7A0
E: The repository 'https://deb.opera.com/opera-stable stable 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.
Unfortunately I am still receiving the same issue. Any ideas?