Unable to install packages on Digital Ocean Ubuntu 18 droplet: Could not find /boot/grub/menu.lst file

Symptoms

• Unable to install packages via Plesk > Tools & Settings > Updates & Upgrades > Add/Remove Components or from Extensions on Digital Ocean Ubuntu 18 droplet with the error:

  PLESK_INFO: Removing linux-image-4.15.0-38-generic (4.15.0-38.41) …
  /etc/kernel/postrm.d/initramfs-tools:
  update-initramfs: Deleting /boot/initrd.img-4.15.0-38-generic
  /etc/kernel/postrm.d/x-grub-legacy-ec2:
  Searching for GRUB installation directory … found: /boot/grub
  Searching for default file … found: /boot/grub/default
  Testing for an existing GRUB menu.lst file …

  Could not find /boot/grub/menu.lst file. Would you like /boot/grub/menu.lst generated for you? (y/N) /usr/sbin/update-grub-legacy-ec2: line 1101: read: read error: 0: Bad file descriptor

  run-parts: /etc/kernel/postrm.d/x-grub-legacy-ec2 exited with return code 1
  dpkg: error processing package linux-image-4.15.0-38-generic (–remove):
  installed linux-image-4.15.0-38-generic package post-removal script subprocess returned error exit status 1
  Errors were encountered while processing:
  linux-image-4.15.0-38-generic
  E: Sub-process /usr/bin/dpkg returned an error code (1)

• Plesk update is failing with the same error.

Cause

This is Plesk bug with ID #PCI-164,which will be fixed in future Plesk updates.

Resolution

As a workaround, apply the following steps:

1. Connect to the server via SSH;

2. Recreate the missing /boot/grub/menu.lst file:

   # mv /boot/grub/menu.lst~ /boot/grub/menu.lst

3. Reinstall the system packages:

   # DEBIAN_FRONTEND=noninteractive apt-get install -y -f