[RPi3B] Fails to boot (ACT LED blinks 3x) after raspi-firmware 1:1.20260521-2 upgrade on Trixie

[squirrellyidiot]

Describe the bug
Raspberry Pi 3 model B becomes completely unbootable immediately after upgrading raspi-firmware from version 1:1.20260521-1 to 1:1.20260521-2 on Raspberry Pi OS / Debian Trixie (arm64). Green ACT LED gives 3x blink, indicating start.elf could not be located. Rainbow splash screen is shown for a brief moment when connected to HDMI screen, but screen becomes black with no console after.

Other packages in update batch do not cause the issue (initramfs-tools, linux-image-rpi-v8, rpi-eeprom, flashrom). Issue only happens when upgrading raspi-firmware.

To reproduce
Flash Raspberry Pi OS Lite Trixie arm64 to SD card, boot Raspberry Pi 3B, and run system update. Reboot.

Expected behaviour
Pi will boot normally.

Actual behaviour
Pi gives 3 blinks on green ACT LED after reboot attempt and fails to boot.

System
Model: Raspberry Pi 3 Model B
OS and version: Raspberry Pi reference 2026-04-21
Generated using pi-gen, https://github.com/RPi-Distro/pi-gen, d2f70c5af1f007626c52f773f8e22209c4a34d38, stage2
vcgencmd version: May 21 2026 11:21:57
Copyright (c) 2012 Broadcom
version 288930ab4712b99596f32732664aaaeb881ef1e0 (clean) (release) (start)
Kernel version: Linux raspberrypi 6.18.33+rpt-rpi-v7 #1 SMP Raspbian 1:6.18.33-1+rpt1 (2026-06-01) armv7l GNU/Linux

Additional context
-Issue is fully reproducible and has been tested many times.
-Has been tested with different SD cards with same results
-Has been tested with two different known-good Cannakit 2.5A power supplies with same results
-Other packages in the same upgrade batch do not cause failure, only raspi-firmware 1:1.20260521-2
-Failure occurs before any SD activity happens via green LED

[pelwell]

Can you confirm that you have made no modifications to config.txt? How about any customisations using RPi Imager?

[squirrellyidiot]

In my config.txt, I had bluetooth disabled as well as an overclock. I also had my gpu memory set to 16 since I'm not using a desktop environment. I commented them out during testing to rule them out.

For customization in RPi imager, I set user/pass, configured wlan, set locale, and enabled SSH. Enabling wlan and ssh via the imager didn't work, and I ended up having to connect it to a monitor to set it up anyway.

Here's my config if it'll help:

# For more options and information see
# http://rptl.io/configtxt
# Some settings may impact device functionality. See link above for details

# Uncomment some or all of these to enable the optional hardware interfaces
#dtparam=i2c_arm=on
#dtparam=i2s=on
#dtparam=spi=on

# Enable audio (loads snd_bcm2835)
dtparam=audio=on

# Additional overlays and parameters are documented
# /boot/firmware/overlays/README

# Automatically load overlays for detected cameras
camera_auto_detect=1

# Automatically load overlays for detected DSI displays
display_auto_detect=1

# Automatically load initramfs files, if found
auto_initramfs=1

# Enable DRM VC4 V3D driver
dtoverlay=vc4-kms-v3d
max_framebuffers=2

# Don't have the firmware create an initial video= setting in cmdline.txt.
# Use the kernel's default instead.
disable_fw_kms_setup=1

# Disable compensation for displays with overscan
disable_overscan=1

# Run as fast as firmware / board allows
arm_boost=1

[cm4]
# Enable host mode on the 2711 built-in XHCI USB controller.
# This line should be removed if the legacy DWC2 controller is required
# (e.g. for USB device mode) or if USB support is not required.
otg_mode=1

[cm5]
dtoverlay=dwc2,dr_mode=host

[all]

#over_voltage=4
#arm_freq=1350
#gpu_mem=16
dtoverlay=disable-bt

[pelwell]

Thanks - I'm just gathering information for when I have a 3B to hand.

[pelwell]

Am I right to assume that the 20260513 firmware was OK? If not, what was the last-known-good firmware?

[squirrellyidiot]

1:1.20260521-1 is the most recent working firmware

[pelwell]

Yes, it helps if you read all of the words.

Pulling apart those two releases reveals identical payloads, as least as far as the firmwares are concerned. In fact, I think the only differences are to a post update script which now includes:

# Ensure the target directory exists. See https://bugs.debian.org/887062
mkdir -p "${firmware_dst}"

and to the changelog, which gains:

raspi-firmware (1:1.20260521-2) trixie; urgency=medium

  * initramfs hook: create /boot/firmware before copying initrd

 -- Serge Schneider <serge@raspberrypi.com>  Mon, 08 Jun 2026 18:30:38 +0100

Did I get that right, @XECDesign ?

[XECDesign]

Yup, this is the only change - RPi-Distro@166d874

[squirrellyidiot]

This is getting kinda far out of my wheelhouse. I don't really have much of a compsci background, so it's hard for me to interpret your last post, pelwell. All I know is my pi wouldn't boot after I updated it, I took some troubleshooting steps and found that I could reproduce it in a way that an average user would get out of the box. Is that not a valid bug report?

Fwiw, I did check to see if there was a changelog, but my pi returned

Error: Failed to fetch changelog:/raspi-firmware.changelog Changelog unavailable for raspi-firmware=1:1.20260521-2

[pelwell]

None of this is doubting your experience, and I'm sure all will become clear with a 3B to try it, it's just very puzzling how such a harmless looking change could be so fatal.

[pelwell]

Hmm - it worked for me. This was my process:

1. Start with a non-Lite 64-bit Trixie image (2026-04-21), with my usual configuration via RPi Image - a user added, hostname set, SSH enabled. I also edited config.txt to enable the UART console and extra UART logging (enable_uart=1 and uart_2ndstage=1).
2. Boot it and wait for the login prompt.
3. Log in - for me it was via the UART console.
4. Go through this sequence. This is the unedited history. It includes a few failed attempts to install the -1 release, and a detour to disable the sudo password:

   1  sudo apt update
   2  sudo raspi-config
   3  sudo apt update
   4  sudo apt list --upgradable | grep raspi-firmware
   5  sudo apt install raspi-firmware=1.20260521-1
   6  sudo apt install raspi-firmware=1:1.20260521-1
   7  apt-cache policy raspi-firmware
   8  sudo apt install raspi-firmware=1:1.20260521-2
   9  ls -l /boot/firmware/
   10  sync
   11  md5sum /boot/firmware/start.elf
   12  sudo reboot
   

   The simplified version is just:

   sudo apt update
   sudo apt install raspi-firmware
   sudo reboot
   

5. Watch it boot.

[pelwell]

Upgrading the remaining packages made no difference - it's still fine.