I'm using Ubuntu 16.04.3 LTS. I've been using it for over a year, updating every couple of months with no problems. Today I updated and I got these strange public key errors. I have no idea what this means nor where to start.
Here are the errors:
Err:9 http://dl.google.com/linux/chrome/deb stable Release.gpg
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 6494C6D6997C215E
Fetched 308 kB in 1s (159 kB/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://dl.google.com/linux/chrome/deb stable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 6494C6D6997C215E
W: Failed to fetch http://dl.google.com/linux/chrome/deb/dists/stable/Release.gpg The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 6494C6D6997C215E
W: Some index files failed to download. They have been ignored, or old ones used instead.
I already tried researching on-line but have found the explanations to be extremely confusing. Please help me understand:
1) What these errors mean.
2) How to fix them.