Raspberry Pi boot issues can be particularly tricky to diagnose because, unlike a regular desktop computer, these tiny machines don’t have a BIOS to help identify what’s wrong. Without proper boot files on the SD card, older Raspberry Pis won’t even generate a video signal. But don’t worry – by following this guide, you’ll be able to identify and fix your Pi’s boot problems in no time.
Solution 1: Check Your Power Supply and Cable
Many Raspberry Pi boot issues that boiled down to power problems, and the power requirements have increased significantly with newer models:
- Raspberry Pi 3: 2.5A recommended
- Raspberry Pi 4: 3.0A recommended
- Raspberry Pi 5: 5.0A recommended
Your Pi won’t even attempt to boot properly if it’s not getting enough stable power, but it might also start booting but freeze at the rainbow screen or reboot randomly.
The easiest way to meet the power requirements, is to use the official Raspberry Pi power supply for your model. While there are third-party options available, the official power supply is specifically designed to handle your Pi’s power characteristics and comes with an appropriate cable that can handle the required current.
If you must use a third-party power supply, make sure it’s rated for the correct amperage and use a short, thick USB cable as longer or thinner cables can cause voltage drop that prevents proper boot.
Solution 2: Install a Fresh Copy of Raspberry Pi OS
One of the most reliable ways to determine if your Pi’s boot problem is caused by a fault in the Raspberry Pi itself is to try a fresh installation of Raspberry Pi OS on a new SD card. If you haven’t reinstalled your Pi before, then you can follow our detailed guide on how to set up Raspberry Pi OS.
If your device boots up successfully after a fresh installation, your original problem was likely caused by a corrupted SD card or operating system. To determine which of them is at fault, you can create a backup image of your original SD card using the ‘dd’ command in Terminal (on macOS/Linux) or HDD Raw Copy Tool (on Windows), then try reinstalling the OS on your original card. If it boots with a fresh OS, your old installation was corrupted. If it still fails, the SD card itself is likely damaged and should be replaced.
However, if your Pi still won’t boot with a new SD card and fresh OS installation, you should move on to checking the LED indicators or the boot diagnostics screen (covered in Solution 3) to help diagnose whether you’re dealing with a hardware fault in the Pi itself.
Solution 3: Check Boot Diagnostics Information
The Raspberry Pi has two ways to communicate boot problems, and the first of them are LED patterns. Here’s what the patterns mean:
| LED Pattern | Meaning | What to Do |
|---|---|---|
| ACT LED blinking irregularly | Normal boot in progress | This is good! Wait for boot to complete |
| ACT LED not blinking at all | Can’t read SD card | Check SD card is inserted properly and try Solution 2 |
| 3 flashes | Can’t find start.elf | Try Solution 2 |
| 4 flashes | Corrupt start.elf or no boot code (Pi 4) | Try Solution 2 |
| 7 flashes | Can’t find kernel.img | Try Solution 2 |
| 8 flashes | SDRAM not recognized | Possible hardware fault if Solution 2 doesn’t work |
| PWR LED off/blinking | Power supply issues | Return to Solution 1 to fix power problems |
Newer Raspberry Pis (model 4b and 5) also display boot diagnostics information directly on your HDMI display if one of the following conditions is met:
- There’s no SD card (or other boot devices) connected to the Pi.
- The bootloader has failed to boot.
Here’s an example of how the diagnostics screen looks like:
As you can see, no bootable partitions were found. That’s because I removed my SD card to trigger the diagnostics screen. In the real-world, you might also see something like this:
Boot mode: USB-MSD (04) order f256
PCIe timeout: 0x0000008f
USB XHC init failed
Boot mode: NVME (06) order f25In this case, the Pi is trying to boot from USB storage (“Boot mode: USB-MSD”), then from an NVMe drive, but failing at both. The “PCIe timeout” errors suggest there might be hardware initialization problems. In this case, since we want to boot from an SD card, we should check that our card is properly inserted and try Solution 2 to rule out software issues before considering hardware problems.
Solution 4: Fix Display Output Problems
If your Pi is booting (indicated by irregular flashing of the green LED) but you’re not seeing anything on your display, then the problem could be with the display output.
First, double-check that the micro-HDMI to HDMI cable is fully inserted into the HDMI port. I recommend you use the HDMI0 port (the one closest to the USB-C power connector) when connecting a 4K display as the second port (HDMI1) won’t work with 4K60 displays.
Still nothing? Then you should try a different micro-HDMI to HDMI cable. Buying the official one from the Raspberry Pi store is your best bet, but any high-quality cable rated for 4K should work.
You can also modify the /boot/config.txt file to force specific display settings. To do this, you’ll need to:
- Remove the SD card and insert it into another computer.
- Open the “boot” partition using a file explorer.
- Find and edit the config.txt file using a text editor.
Here are the most effective settings to try (add or uncomment these lines):
# Force HDMI output even if no display detected
hdmi_force_hotplug=1
# Try safe mode if you're getting no display
hdmi_safe=1
# Set specific HDMI mode (if your display isn't being detected correctly)
hdmi_group=2
hdmi_mode=82
# Increase HDMI signal strength if you're getting flicker or no display
config_hdmi_boost=4Add these settings one at a time, testing between each change. If one setting doesn’t work, remove it before trying the next one.
Solution 5: Update Your Pi’s Bootloader
This solution is mostly for Raspberry Pi 4 and 5 owners, as these models use an EEPROM chip to store their boot code instead of keeping it on the SD card like previous models did.
Start by downloading the latest version of the Raspberry Pi Imager from the official Raspberry Pi website. Once installed, connect a blank SD card to your computer and launch the Imager. Instead of selecting an operating system, click Choose OS and navigate to Misc utility images.
From there, select Bootloader and then Boot Recovery. This will create a special SD card that updates your Pi’s bootloader to the latest version.
Once you’ve written the recovery image to your SD card, insert it into your Pi and power it on. You should see the green activity LED blink rapidly with a pattern that indicates the update is in progress. After about 10 seconds, the LED should stay on steadily for a few seconds if the update was successful. Power off your Pi, remove the recovery SD card, and try booting again with your normal SD card.
If your Pi still won’t boot after trying all these solutions, you’re likely dealing with a deeper hardware issue. While Raspberry Pis are generally quite reliable, they can fail if exposed to power surges, static electricity, or incorrect voltages on their GPIO pins. In this case, you’ll probably need to purchase a new Raspberry Pi or consider one of the many excellent Raspberry Pi alternatives available today.
Images by David Morelo.
