Known Issues

This page documents known hardware and firmware issues affecting ChromeOS devices when running MrChromebox firmware. For OS-specific compatibility issues (drivers, functionality under Linux/Windows), see the chrultrabook documentation.

Platform Support Limitations

ARM-Based Devices (Not Supported)

All ARM-based Chromebooks: The MrChromebox project does not support these devices at all. This includes devices with MediaTek, Rockchip, Qualcomm, or NVIDIA Tegra processors. MrChromebox firmware only supports Intel and AMD x86_64 platform devices.

End of Life (EOL) Devices

Devices past their Auto Update Expiration (AUE) date have the following restrictions:

• RW_LEGACY updates blocked: Cannot install or update RW_LEGACY firmware (existing installations continue to work)
• Stock firmware restoration blocked: Cannot restore stock firmware using the Firmware Utility Script (prevents users from getting stuck on an unsupported ChromeOS version)
• UEFI Full ROM firmware: Still fully supported and updated

Affected platforms: SandyBridge, IvyBridge, Haswell, Broadwell, BayTrail, Braswell, and Skylake.

See Google's AUE Policy for specific device EOL dates.

Firmware-Specific Issues

RW_LEGACY Firmware Limitations

RW_LEGACY firmware has inherent limitations compared to UEFI Full ROM:

All Devices:

• No UEFI NVRAM: Cannot save boot order or UEFI settings persistently. Boot order resets after each boot.
• Limited boot options menu: No support for features like boot order modification, TPM management or Secure Boot.

Device-Specific:

• GeminiLake: Legacy Boot Mode/Alternative Firmware menu works but does not show payload list. Boot device selection is non-functional.
• CometLake: Chromebooks do not currently have functional Legacy Boot Mode due to bugs in Google's stock firmware.

Workaround: For the best experience with alternate OSes, use UEFI Full ROM firmware instead of RW_LEGACY.

AMD Platform Issues

AMD Stoneyridge (pre-Zen):

• Most Stoney Ridge devices do not currently have functional Legacy Boot Mode due to bugs in Google's stock firmware.

AMD Cezanne (Zen 3):

• Legacy Boot Mode/Alternative Firmware menu works, edk2 boots, but screen backlight is off during firmware/boot.
• Backlight functions normally once the OS loads.
• Workaround: Use UEFI Full ROM firmware for proper backlight control throughout the boot process.

Google Security Chip (CR50/Ti50) Issues

Ti50 Devices (2022 and newer):

• RO Firmware Verification: Ti50 performs additional verification of RO firmware regions. If RO verification fails, the device will not boot, even to recovery mode.
• Recovery Requirement: Failed RO verification requires physical intervention - either external flashing hardware or a SuzyQable cable.
• Affected Actions: Installing UEFI Full ROM, restoring stock firmware, or any operation that modifies normally write-protected regions.

Risk Mitigation:

• Always create a firmware backup before flashing UEFI Full ROM on Ti50 devices
• Understand that reverting to stock firmware carries higher risk on Ti50 devices
• Have recovery hardware available (SuzyQable or CH341A programmer) before attempting firmware modifications

See Write Protection: Ti50 Considerations for detailed information.

Device-Specific Issues

Severe Hardware Issues

Samsung Chromebook 3 (CELES):

• Numerous hardware bugs make it difficult to use reliably
• Issues include unstable USB, intermittent display problems, and poor thermal management
• Recommendation: Avoid purchasing; not worth the hassle

Samsung Galaxy Chromebook (KOHAKU):

• Badly designed hardware with multiple failure modes
• Deteriorating trackpad grounding causes erratic behavior over time
• Possibly faulty backlight circuit leading to premature failure
• Recommendation: Avoid purchasing; known to fail prematurely

Minor Device Issues

Samsung Chromebox Series 3 (STUMPY):

• VGA output through the DVI port is completely non-functional
• DisplayPort output is non-functional under Windows (but works fine at boot and under Linux)
• Workaround: Use HDMI output, or use Linux if DisplayPort is required

Common User Issues and Solutions

First Boot After Firmware Flash Takes Forever

Symptom: After flashing UEFI Full ROM firmware, the first boot takes 20-60 seconds with a black screen.

Cause: RAM training - the firmware must re-run RAM training when changing firmware types, or when the MRC cache is empty or invalid.

Solution: This is normal behavior. Subsequent boots will be much faster (typically under 5) as the training data is cached. See FAQ: Why does my device take forever to boot?

Device Won't Boot After Firmware Flash

Possible causes:

1. Still in RAM training - Wait up to 90 seconds, especially on newer devices with DDR5
2. Ti50 RO verification failure - See Ti50 issues above
3. Corrupted firmware flash - Recovery via external flashing may be required

Recovery steps:

1. Wait at least 90 seconds before assuming failure
2. Try force-powering off (hold power button 10+ seconds) and power on again
3. Try a hard reset (press Refresh + power simltaneously, then release)
4. If still not booting, see Unbricking Guide

Can't Enter Developer Mode / Recovery Mode

Chromebooks:

• Ensure battery is plugged (important!!) in and charged (>20%)
• Try the key combination multiple times
• On some devices, timing matters - try holding keys before pressing power
• Must use built-in keyboard for accessing Recovery and Developer Modes

Chromeboxes:

• Locate the physical recovery button (usually a small pin-hole)
• Hold recovery button while powering on
• Release after 3-5s

If Developer Mode screen appears but won't proceed:

• On R117+, the warning screen timeout changed from 30s to 2 minutes
• Press CTRL+D to boot immediately instead of waiting

Firmware Utility Script Shows "Update Available" But Update Fails

Cause: Usually network connectivity issues or download interruptions.

Solutions:

1. Check internet connection
2. Run the script again/flash again
3. If using corporate/school network, try a different network (may be blocking firmware downloads)
4. Check script output for specific error messages
5. Use a VPN

Boot Priority Keeps Resetting / Can't Save Boot Order (RW_LEGACY)

Cause: RW_LEGACY firmware does not support UEFI NVRAM for persistent boot settings.

Solutions:

• Switch to UEFI Full ROM firmware for persistent boot order
• Or accept that boot device selection must be done manually each time via the firmware boot menu

Platform-Specific Issues

SandyBridge/IvyBridge (2012-2013)

• Some devices have quirks with USB 3.0 controllers
• Lower performance due to older hardware (expected)

Haswell/Broadwell (2014-2015)

• Generally well-supported with few issues
• EC firmware updates on Chromebooks provide improved keyboard support

BayTrail/Braswell (2014-2016)

• Some devices have eMMC compatibility issues under Windows (requires specific drivers)
• Touchscreen support varies by device and OS

Skylake/Kabylake (2016-2018)

• Mature platform with excellent support
• Most hardware works well under both Linux and Windows
• EC firmware updates on Chromebooks improve keyboard and power management

Apollolake/GeminiLake (2017-2019)

• GeminiLake RW_LEGACY has non-functional boot menu (use CTRL+L)
• Otherwise well-supported

Cometlake/Tigerlake (2020-2021)

• Excellent support with latest firmware
• Few known issues

Alderlake/Alderlake-N/Raptorlake (2022-2024)

• Modern platform with active development
• Some devices have Ti50 security chip - see Ti50 issues above
• Fixed RW_LEGACY payload on some devices (cannot be updated)

Meteor Lake (2024+)

• Newest supported platform
• Limited device availability; support being actively developed

Getting Help

If you encounter an issue not listed here:

1. Check the FAQ: Many common questions are answered in the FAQ
2. Search existing issues: Check the Firmware Issue Tracker to see if it's already reported
3. Ask in the right place:
   • Firmware bugs → Firmware Issue Tracker
   • Script issues → Scripts Issue Tracker
   • OS compatibility/drivers → chrultrabook forums
   • General help → chrultrabook forums

For OS-specific issues (drivers, functionality under Linux/Windows), see the chrultrabook documentation.