Your Debian system is failing to boot due to several critical errors related to missing or unreachable block devices and filesystems. Here’s a breakdown of the issues visible in your screenshot:

Key Errors

1. blkid: not found The system cannot find the blkid command, which is essential for identifying block devices (like disks and partitions).

2. mdadm: not found The mdadm tool, used for managing MD (software RAID) devices, is missing. This suggests your system may rely on RAID, but the necessary tools are unavailable.

3. /usr/bin/plymouth: not found Plymouth, which handles graphical boot animations, is missing. This is less critical but indicates a deeper issue with the filesystem.

4. Gave up waiting for root file system device The system cannot find or mount the root filesystem, which is required to continue booting.

5. ALERT! UUID=... does not exist The system is configured to mount a root filesystem by its UUID, but that UUID cannot be found on any available block device.

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Common Causes

• Missing or corrupted /usr or /bin directories: Critical commands like blkid and mdadm are usually located here.
• Failed or missing RAID array: If your root filesystem is on a RAID array, the array may not be assembled.
• Incorrect or missing initramfs: The initial RAM filesystem (initramfs) may not include the necessary tools or modules to mount the root filesystem.
• Disk or partition issues: The disk containing the root filesystem may be physically damaged, disconnected, or its partition table may be corrupted.

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Steps to Troubleshoot

1. Check Boot Arguments

• At the boot prompt (GRUB), edit the boot entry:
  • Highlight your Debian entry and press e.
  • Look for the line starting with linux. Ensure the root= argument points to the correct device (e.g., /dev/mdX or /dev/sdXY).
  • If you suspect RAID issues, add break=init to drop to a shell before the root filesystem is mounted.

2. Drop to a Rescue Shell

• If you can’t boot normally, use a Debian Live CD/USB or another rescue environment.
• Once booted, open a terminal and run:

  bash
  Copy
  chroot /target /bin/bash
  

  (Replace /target with the mount point of your root filesystem, if mounted.)

3. Check RAID Status

• If you use RAID, check the status of your arrays:

  bash
  Copy
  mdadm --detail --scan
  mdadm --assemble --scan
  

• If mdadm is missing, install it from the rescue environment:

  bash
  Copy
  apt-get update && apt-get install mdadm
  

4. Reinstall Critical Tools

• From the rescue environment, reinstall missing tools:

  bash
  Copy
  apt-get update
  apt-get install --reinstall util-linux mdadm plymouth
  

5. Update initramfs

• Rebuild the initial RAM filesystem to ensure all necessary tools and modules are included:

  bash
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  update-initramfs -u -k all
  

6. Check Filesystem Integrity

• Run fsck on your root filesystem:

  bash
  Copy
  fsck /dev/sdXY
  

  (Replace /dev/sdXY with your actual root partition.)

7. Verify /etc/fstab and GRUB Configuration

• Ensure /etc/fstab and your GRUB configuration (/boot/grub/grub.cfg) reference the correct devices or UUIDs.

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If You Need More Help

• Let me know if you can access a rescue environment or if you need step-by-step guidance for any of the above.
• If you’re unsure about your disk setup (RAID, LVM, etc.), I can help you figure it out.