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So this error has been popping up a lot so I thought I'd resolve it:

W: GPG error: precise Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 535C743689107B44

So I did some research and tried these solutions

gpg --keyserver hkp:// --recV 535C743689107B44


sudo apt-key adv --recv-keys 535C743689107B44

both of which terminated with this message

gpgkeys: key 535C743689107B44 not found on keyserver
gpg: no valid OpenPGP data found.
gpg: Total number processed: 0

Any insights are appreciated

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up vote 1 down vote accepted

Maybe the GPG-key is not there (anymore).

If you want to install CFEngine Community Linux Packages: from(

exerpt: CFEngine 3 Linux Distributions: Download and install the CFEngine GPG key(changed # to sudo because of formating):

sudo wget

sudo apt-key add gpg.key

sudo rm gpg.key

Add the repository to the apt list of sources. If the add-apt-repository utility is installed on your system, you may simply run:

sudo add-apt-repository

... follow instructions on the website.

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The second approach mentioned in this link worked for me. Manually download the key and add it. The link provides step by step procedure to fix the error happening due to missing key.

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