When upgrading Ubuntu on AWS EC2 instances, particularly from older versions like 13.10 to 14.04, you might encounter this common GRUB configuration file conflict. The system detects that your current /boot/grub/menu.lst differs from the maintainer's version, even if you personally haven't modified it.

AWS EC2 instances typically come with pre-configured GRUB settings that:

• Optimize boot parameters for virtualized environments
• Include AWS-specific kernel parameters
• May contain custom console settings for EC2's Xen hypervisor

The safest option is to keep the local version during the upgrade prompt. Here's why:

# Example of AWS-specific GRUB parameters you might find:
kernel /boot/vmlinuz-3.11.0-15-generic root=UUID=ebs-vol-123 ro 
console=hvc0 xen_emul_unplug=unnecessary

After completing the upgrade, verify your GRUB configuration:

sudo diff /boot/grub/menu.lst /usr/share/grub/menu.lst~
# Check for AWS-specific parameters
grep -E 'xen|console|root=' /boot/grub/menu.lst

Only choose "install the package maintainer's version" if:

• You're moving to a new instance type
• Experiencing boot issues
• Upgrading across multiple LTS versions

For scripted upgrades, use this non-interactive approach:

sudo DEBIAN_FRONTEND=noninteractive do-release-upgrade -f DistUpgradeViewNonInteractive
sudo apt-mark hold grub-common grub-pc

If you encounter problems after upgrade:

# Recover using AWS Systems Manager
aws ssm send-command --instance-id i-1234567890abcdef0 \
--document-name "AWS-RunShellScript" \
--parameters 'commands=["sudo update-grub"]'

When upgrading Ubuntu on AWS EC2 instances (especially older versions like 13.10 to 14.04), you might encounter this prompt about /boot/grub/menu.lst modifications. This typically occurs because:

• AWS modifies GRUB configuration during instance provisioning
• The cloud-init process makes adjustments for virtualization
• Previous unattended upgrades may have altered the file

The upgrade process presents several choices for handling the conflict:

1. install the package maintainer's version
2. keep the local version currently installed
3. show differences between versions
4. side-by-side difference view
5. 3-way difference comparison
6. 3-way merge (experimental)
7. start a shell to examine

For AWS EC2 instances, the safest choice is to:

# Select option 2: keep the local version
# This preserves AWS-specific configurations

After completing the upgrade, verify GRUB configuration:

sudo update-grub
sudo grub-install /dev/xvda  # For older EC2 instances

If you're curious about the modifications:

# Use option 3 or 4 to view differences
# Sample output might show AWS-specific entries:
# - console=hvc0
# - xen_blkfront.sda_is_xvda=1
# - root=LABEL=cloudimg-rootfs

After upgrade completion:

# Check boot configuration
ls -l /boot/grub/menu.lst
cat /proc/cmdline

# Verify instance connectivity
ping -c 3 google.com
ssh your-instance.amazonaws.com

Only select option 1 if:

• You're migrating to a non-virtualized environment
• You need new GRUB features not in AWS's version
• You've confirmed backup of current configuration