Apt clean give me error with public key not found

PG error: http://http.debian.net wheezy-backports Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8B48AD6246925553 NO_PUBKEY 7638D0442B90D010
Done...
Also probably related when I try to update plex server how to fix It?

I think you gave me the fix thank you. By any chance do you know the exact method to update Plex server plugin?

root@raspberrypi:~# gpg --recv-keys 8B48AD6246925553 && gpg --export 8B48AD6246925553 |apt-key add -
gpg: requesting key 46925553 from hkp server keys.gnupg.net
gpg: key 46925553: public key "Debian Archive Automatic Signing Key (7.0/wheezy) <ftpmaster@debian.org>" imported
gpg: no ultimately trusted keys found
gpg: Total number processed: 1
gpg: imported: 1 (RSA: 1)
OK
root@raspberrypi:~# gpg --recv-keys 7638D0442B90D010 && gpg --export 7638D0442B90D010 |apt-key add -
gpg: requesting key 2B90D010 from hkp server keys.gnupg.net
gpg: key 2B90D010: public key "Debian Archive Automatic Signing Key (8/jessie) <ftpmaster@debian.org>" imported
gpg: no ultimately trusted keys found
gpg: Total number processed: 1
gpg: imported: 1 (RSA: 1)
OK

Zitat von ryecoaaron

You can't on an RPi. The plex package is not maintained by the package maintainer (not an OMV dev).

This art I figured out but from this it is kind of vague! lol