Downgrade ChromeOS to an Older Version

Documentation Index

Fetch the complete documentation index at: https://mintlify.com/S-PScripts/chromebook-utilities/llms.txt

Use this file to discover all available pages before exploring further.

Many unenrollment and exploit methods only work on specific, older versions of ChromeOS. Downgrading allows you to roll back to a version that still has an unpatched vulnerability — for example, CryptoSmite requires v119 or lower, and Sh1mmer works best below v111. However, downgrading is not always possible: Google introduced kernel version locking (kernver) to restrict how far back a device can recover. Understanding your board and kernver before attempting any exploit is essential.

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Understanding ChromeOS Boards and Kernel Versions

Every Chromebook runs on a specific board (hardware platform). Many exploits target specific boards or version ranges, and recovery images are distributed per-board. Your board name is required to download the correct recovery image.

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Most Common ChromeOS Boards

The most widely encountered boards in the community (by device count) include: dedede (81), octopus (78), nissa (45), coral (40), brya (36), volteer (18), grunt (14), zork (14), enguarde (13), jacuzzi (13), corsola (12), fizz (10), hatch (10), hana (9), nami (9), trogdor (9), brask (8), rex (6), skyrim (5), guybrush (4), kukui (4), strongbad (4), cherry (3), asurada (3), and many more.

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Kernel Versions (Kernver)

Kernver is ChromeOS’s kernel version — a value stored in the TPM that locks the device to a minimum recoverable ChromeOS version. If your kernver is higher than what an exploit requires, you cannot use that exploit. Determining your kernver: Credits: Titanium Network — docs.titaniumnetwork.org/kajigs/versions

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Finding Your Board Name and Model

You need your board name to download the correct recovery image. There are several methods:

Method 1 — chrome://version (easiest)

1. Go to chrome://version/
2. In the Platform section, look at the end — this is your board name (e.g., octopus or dedede).
3. The Customization ID section shows your board model (e.g., phaser360 or boten).

Method 2 — chrome://system

1. Go to chrome://system/ and wait for it to finish loading.

Board name — check any of these fields:

• CHROMEOS_RELEASE_BOARD (board name at start)
• CHROMEOS_RELEASE_BUILDER_PATH (board name at start)
• CHROMEOS_RELEASE_DESCRIPTION (board name at end)
• platform_identity_name

Board model — check any of these fields:

• HWID (board model at start)
• hardware_class (board model at start)
• platform_identity_model

If chrome://system is blocked, press Ctrl + Search + I, enter anything in the description, click Continue, then click the blue “System and app info” text.

Method 3 — Google Play (no shell needed)

1. Go to Google Play.
2. Click your account in the top right → arrow next to your email → Manage accounts on this device.
3. Click the search icon, search device, and scroll down.
4. Look for “Device configuration for” followed by your board name.

Found by SlitheringLizard1.

Method 4 — Android Settings

1. Open Settings → Apps → Android Settings.
2. Scroll to the bottom of the Android settings page.
3. Find “About device (your board name)”.

Method 5 — chrome://connectors-internals

1. Go to chrome://connectors-internals.
2. Find the "deviceModel" field — this is your board model.
3. Enter the board model at cros.tech to look up your board name.

Found by HyperNut.

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Finding Your ChromeOS Version

You may need to confirm your current version before deciding which downgrade target or exploit to use.

Version detection methods

Method 1: Go to chrome://version — look for the version number (e.g., v1xx).Method 2: Open Settings → scroll to About ChromeOS — the version is listed there.Method 3: On the lock screen, press Alt + V — the version appears in the top right as “Google Chrome X”.Method 4: Go to chrome://system/ and check the CHROME VERSION, os-release VERSION, or os-release VERSION_ID fields. If chrome://system is blocked, press Ctrl + Search + I and use the System and app info link.Method 5: Go to chrome://nacl/ — the first line shows your Chrome version.

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Downgrade Methods

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Standard Downgrade via Recovery Image (Anastrophe)

This is the primary method for downgrading ChromeOS using a USB recovery image flashed to the target version. It uses a built-in ChromeOS recovery feature. Requirements:

• USB thumb drive with at least 4 GB of storage (16 GB recommended)
• A personal computer with the Chromebook Recovery Utility extension

Credits: 3kh0/ext-remover, Titanium Network

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Downgrade via Kernver 3 (Shimboot)

For devices on kernver 3, a different approach using Shimboot is used as the bootloader.

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Internet Unrecovery (2023+ NewUI Chromebooks)

This method uses the Internet Recovery tool on newer Chromebooks to downgrade without a USB drive. It has been confirmed working on corsola-steelix (Lenovo 300e Yoga Gen 4 MTK) and similar devices. Requirements:

• A NewUI Chromebook (corsola, nissa, or any 2023+ release date device — release date, not manufacture date)
• Developer Mode disabled

Credits: kilo | kxcv

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Preventing Re-Upgrade After Downgrading

After downgrading, ChromeOS will attempt to auto-update back to the latest stable version. To stay on your downgraded version, you need to block automatic updates. Use CAUB (ChromeOS Auto-Update Blocker) to prevent ChromeOS from upgrading after downgrading. See the CAUB guide for instructions.

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Recovery Image Resources