Symptoms
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Debian or Ubuntu is installed on the server.
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Plesk updates or some extensions installation fail with the following message:
PLESK_ERROR: An error occurred on attempt to install packages.
Attention! Your software might be inoperable.
Please contact product technical support. -
Following warning message could be found in
/var/log/plesk/install/autoinstaller3.log
:W: GPG error: http://repo.cloudlinux.com/kernelcare-debian/8 stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY DC3D600CDEF74BB
OR
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://us-west-2.ec2.archive.ubuntu.com/ubuntu xenial-updates InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5 NO_PUBKEY 3B4FE6ACC0B21F32
OR
Executing: /tmp/apt-key-gpghome.dhoA48mqwL/gpg.1.sh --keyserver hkp://ha.pool.sks-keyservers.net:80 --recv-keys 58118E89F3A912897C070ADBF76221572C52609D
, stderr: Warning: apt-key output should not be parsed (stdout is not a terminal)
gpg: key F76221572C52609D: 7 signatures not checked due to missing keys
Cause
Required public keys are missing.
Resolution
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Login to the server via SSH.
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Add missing keys by executing the following command for each key from the log file, for example:
# sudo apt-key adv –keyserver keyserver.ubuntu.com –recv-keys F76221572C52609D
# sudo apt-key adv –keyserver keyserver.ubuntu.com –recv-keys 40976EAF437D05B5
# sudo apt-key adv –keyserver keyserver.ubuntu.com –recv-keys 6DC3D600CDEF74BBNote: the actual key server name and the key mentioned in the error message should be used in the command above
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In case of Docker installation failure, use the command below:
# sudo apt-key adv –keyserver hkp://ha.pool.sks-keyservers.net:80 –recv-keys F76221572C52609D
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Clean “apt” cache:
# apt-get clean
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Re-install Plesk updates using this guide.