pum update failed on Plesk server: Public key for *.rpm is not installed

Symptoms

• Plesk system updates failed with the following error:

  PLESK_ERROR: 2018-06-22 11:42:40 INFO: pum is called with arguments: ['--update', '--json', '--unsafe', '--', 'kernel-firmware', 'kernelcare', 'mysql-connector-odbc', 'mysql57-community-release', 'procps']
  2018-06-22 11:42:42 INFO: updating packages: procps mysql-connector-odbc kernelcare mysql57-community-release kernel-firmware
  warning: rpmts_HdrFromFdno: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY
  Importing GPG key 0x5072E1F5:
  Userid : MySQL Release Engineering <mysql-build@oss.oracle.com>
  Package: mysql57-community-release-el6-7.noarch (@/mysql57-community-release-el6-7.noarch)
  From : /etc/pki/rpm-gpg/RPM-GPG-KEY-mysql
  warning: rpmts_HdrFromFdno: Header V4 DSA/SHA1 Signature, key ID cdef74bb: NOKEY
  2018-06-22 11:42:57 ERROR: Public key for kernelcare-2.14-11.x86_64.rpm is not installed
  2018-06-22 11:42:57 ERROR: Exited with returncode 1.

• According to the error the update failed on kernelcare-2.14-11.x86_64.rpm package:

  PLESK_INFO: 2018-06-22 11:42:57 ERROR: Public key for kernelcare-2.14-11.x86_64.rpm is not installed

  Note: the package is taken as the example. The package may differ

Cause

The absence of the public key from the corresponding repository.

Resolution

1. Connect to the server via SSH;

2. Check what repository provides the package:

   # yum list kernelcare

   Note: check the 3rd column to find out the repository

3. Check the repository in specified in  /etc/yum.repos.d/kernelcare.repo file:

   # cat /etc/yum.repos.d/kernelcare.repo | grep baseurl
   baseurl=http://repo.cloudlinux.com/kernelcare/$releasever/$basearch

4. Open the repository in browser and copy link  to  public key:
   

5.  Import the public key:

   # rpm --import http://repo.cloudlinux.com/kernelcare/RPM-GPG-KEY-KernelCare

6. Run the system update again.

OR 

1. Connect to the server via SSH;

   Note: if direct SSH access to the server is not possible, contact server administrator for further assistance.

2. Check what repository provides the package:

   # yum list kernelcare

   Note: check the 3rd column to find out the repository

3. Disable  3rd party repository by setting enabled=0 in /etc/yum.repos.d/kernelcare.repo file.