Plesk update or component installation fails on Debian or Ubuntu: The following packages have unmet dependencies

Symptoms

• Installing Plesk update or component on a server with Debian or Ubuntu fails:

  Note: Package names in the error message might differ.

  E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).
  ---X--- `apt-get` output ---------------------
  Reading package lists...
  Building dependency tree...
  Reading state information...
  You might want to run 'apt-get -f install' to correct these:
  The following packages have unmet dependencies:
  linux-headers-generic : Depends: linux-headers-4.4.0-XXX-generic but it is not going to be installed
  postfix-pcre : Depends: postfix (= 3.1.0-3ubuntu0.2) but 3.1.0-3ubuntu0.3 is to be installed

• Attempts to manually run the command apt-get upgrade fail with a similar error:

  Note: Package names in the error message might differ.

  # apt-get upgrade
  Reading package lists... Done
  Building dependency tree
  Reading state information... Done
  You might want to run 'apt-get -f install' to correct these.
  The following packages have unmet dependencies:
  linux-headers-generic : Depends: linux-headers-4.4.0-112-generic but it is not installed
  E: Unmet dependencies. Try using -f.

Cause

Package dependencies are in the inconsistent state.

Resolution

1. Connect to the server using SSH.

2. Try forcing APT package manager to resolve dependencies automatically:

   # apt-get install -f

   Note: If that does not resolve the issue, contact system administrator to resolve the inconsistent state of packages dependencies.