Fixing 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.hhvm.com trusty InRelease: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY B4112585D386EB94

I was trying to update one of my server that has some HHVM repositories and received this error “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.hhvm.com trusty InRelease: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY B4112585D386EB94”

root@someserver:~# apt-get update
Get:1 http://dl.hhvm.com trusty InRelease [2,396 B]
Err http://dl.hhvm.com trusty InRelease
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---SNIP---- 
Fetched 2,396 B in 4s (479 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://dl.hhvm.com trusty InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY B4112585D386EB94
W: Failed to fetch http://dl.hhvm.com/ubuntu/dists/trusty/InRelease
W: Some index files failed to download. They have been ignored, or old ones used instead.

Ran some google search and found that you can simply update the new key from Ubuntu Keyserver.

root@someserver:~#  apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys B4112585D386EB94
Executing: gpg --ignore-time-conflict --no-options --no-default-keyring --homedir /tmp/tmp.tL1nZW6cuE --no-auto-check-trustdb --trust-model always --keyring /etc/apt/trusted.gpg --primary-keyring /etc/apt/trusted.gpg --keyring /etc/apt/trusted.gpg.d/chris-lea-redis-server.gpg --keyring /etc/apt/trusted.gpg.d/ondrej-php.gpg --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys B4112585D386EB94
gpg: requesting key D386EB94 from hkp server keyserver.ubuntu.com
gpg: key D386EB94: public key "HHVM Package Signing <opensource+hhvm@fb.com>" imported
gpg: Total number processed: 1
gpg:               imported: 1  (RSA: 1)
root@someserver:~# apt-get update
Get:1 http://dl.hhvm.com trusty InRelease [2,396 B]
Get:2 http://dl.hhvm.com trusty/main amd64 Packages [1,776 B]
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---SNIP----
Fetched 4,172 B in 4s (898 B/s)
Reading package lists... Done
root@someserver:~#

Hope this helps someone else who’s had the same issue as I did.