[SOLVED] W: error during signature verification NO_PUBKEY

I am using old laptop hp dv5157eu and have just installed Zorin OS 9 Lite 32-bit

I opened terminal and ran 'sudo apt-get update' but encountered an error at the end of this process ....

Code:

margaret@dv5000-zorin9-32bit:~$ sudo apt-get update
Hit http://ppa.launchpad.net trusty InRelease                                 
Ign http://extras.ubuntu.com trusty InRelease                                 
Ign http://dl.google.com stable InRelease                                     
Ign http://ppa.launchpad.net trusty InRelease 
...etc...
...etc...
Hit http://gb.archive.ubuntu.com trusty/universe Translation-en_GB             
Hit http://gb.archive.ubuntu.com trusty/universe Translation-en               
Fetched 1,400 kB in 10min 0s (2,331 B/s)                                       
Reading package lists... Done
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://deb.opera.com stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 63F7D4AFF6D61D45

W: Failed to fetch http://deb.opera.com/opera/dists/stable/InRelease 

W: Some index files failed to download. They have been ignored, or old ones used instead.
margaret@dv5000-zorin9-32bit:~$

I only see one browser Firefox and cant see the Opera browser so I'm puzzled that there is an error with Failed to fetch http://deb.opera.com/opera/dists/stable/InRelease

I notice there is an entry in my sources list for opera.

I also noticed in the Software & Updater window under the 'Authentification' tab there is an entry 'Opera Software Archive Automatic Signing Key', if I select this there is a button called 'Import Key File...' if I click this, will it resolve the error?

I'm still fairly new to linux so any help would be appreciated.

I found a solution to this error message, I was told to add the gpg key manually through terminal window .....

Code:

$ sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 63F7D4AFF6D61D45

Then run....

Code:

$ sudo apt-get update

...and the warning message is gone. many thanks to oldos2er over at http://ubuntuforums.org/ for this solution.

For future reference:

viewtopic.php?f=5&t=2247