Raspberry Pi Troubleshooting

In issue 60 of our favorite magazine, The MagPi, they did a phenomenal troubleshooting guide.  Rather than recreate the wheel, we thought we would offer our own version their guide to give all Raspberry Pi users a one-stop place to troubleshoot their Raspberry Pi.

The Raspberry Pi is Probably Fine

Your first instinct may be that you’ve done everything correctly, so the Raspberry Pi must be at fault. This reaction is natural, however, each Raspberry Pi is tested once it leaves the production line.  We know, we've been there to see it in person!  Your Pi definitely worked before it left the factory, and the chances of it turning up dead on arrival (DOA) are very slim. Of course, in the unlikely case that you’ve gone through this entire article and come to the conclusion that your Raspberry Pi is faulty, contact us and we will do our best to help.  Please cite your order number when you email us!

The Essentials

You’ll need two things to make sure your Raspberry Pi is working. The main one is a microSD card, which you need to load with an operating system. You will also need a monitor or TV to connect to the Pi via an HDMI cable, and a keyboard and mouse to use it properly. 

Reusing Old SD Cards

You’ve taken the SD card from an old Raspberry Pi that you haven’t used for a couple of years and plugged it into a brand-spanking new Pi 3A+. Is it having trouble booting? It’s more than likely you’ll need to use a fresh SD card in your new computer. 

Raspberry Pi 4 Recovery

If your Raspberry Pi 4 will not boot, it is possible that the SPI EEPROM has become corrupted.

To check, remove the SD card, disconnect the device from power, then reconnect it. If the green LED does not flash, you will need to reprogram the EEPROM:

  1. Download the bootloader
    SHA-256: 444e0f68aa21d5b4e158259061de55738d36a1986e2ced14bb14d7af1a04881c
  2. Extract it to an empty FAT-formatted SD card and insert it into your Raspberry Pi 4
  3. Connect the power and wait for the green LED to flash quickly


Things to Check

Check all the connections

This may seem obvious, but it’s always worth wiggling a few cables. You should pay close attention to the SD card: make sure it’s pushed all the way in on a Raspberry Pi Zero or Pi 3, and properly clicked into place in an A+, B+, or Pi 2. The HDMI cable should also be checked at both ends.

Check the power

Are you using the correct power supply? Are you plugging it into the correct port on a Pi Zero? For a Raspberry Pi 3, a 2.5 amp power supply is recommended, while other models can use the same, or a 2 amp supply. Check that the power supply works on another device before giving up on your Pi.

Faulty OS

It’s possible that the operating system wasn’t installed properly on the SD card. The Pi might not boot up properly, or you might see a black screen when you turn it on. The green ACT LED near the power supply input (PWR IN) will blink rapidly if it is able to read the card. If reinstalling doesn’t fix the problem, try downloading NOOBS or the OS image again. The OS can sometimes be corrupted during downloading.

Check the monitor

Just double-check it is turned on and set to the correct input.  Also, it is important to note that the Pi will default to composite output if no HDMI is detected.  So, if you connect your HDMI cable after booting, you likely will see nothing on the screen.


Best practices for installation


New Out Of the Box Software, or NOOBS, is a series of files designed to be saved on a blank SD card. Download the zip file to the card and extract everything. This makes sure that all the files you need on the SD card are there. Delete the original zip file, and put the card into your Raspberry Pi.

Important: your Raspberry Pi requires that NOOBS be installed onto an SD card that is formatted FAT32.  By default, SDXC cards that are bigger than 32 GB usually are NOT formatted FAT32.  Learn more about SDXC formatting here.


When installing Raspbian or any other OS on its own, you can always write the
image directly to the SD card. Etcher is the best app for this.  Check out the MagPi's excellent video on Etcher

Boot problems

Check the ACT LED

There’s a green LED on the corner near the power supply input that blinks when the SD card is being accessed. It’s labelled ACT, and it can be used to determine whether or not the SD card can be read.  The LED should blink erratically when reading from the card during the boot process. If it’s not blinking when the Pi is switched on, it means the card cannot be read.

Waiting on a blown fuse

If no power is being delivered to the Raspberry Pi and the fault isn’t with the power supply, the polyfuse (resettable fuse) on the Pi may have blown – note that there isn’t one on the Pi Zero. Unfortunately, the only solution to this is to wait a few days for it to reset. Trying to turn it on before it has recovered will probably blow the fuse again and reset the wait period.

Not enough power

The power LED will not light up if the voltage from the power supply drops below 4.65 volts. Check the power supply and replace it if you need a higher voltage.  To check power, put a multimeter on GPIO pins 4 (5V) and 6 (ground).

Analog video

The Raspberry Pi A+, B+, 2, and 3 can output an analog composite video signal through the headphone jack. If it’s your first time using this feature, make sure your cable works.  The proper pinout is shown at right.
If you’re using NOOBS, you can force it to change the video output during the first ten seconds of booting by pressing 3 for PAL/UK output, and 4 for NTSC video output.


Changing video outputs in NOOBS

NOOBS has four different video output options that you can change during the first ten seconds of booting. 1 is a normal HDMI output, 2 is safe HDMI, 3 is PAL composite, and 4 is NTSC composite. If you don’t have a keyboard on the Pi, you can edit the recovery.cmdline file on the SD card from another computer and add display=X, where X is one of the listed options.

Updating an old card

Not all old Raspbian SD cards will work on newer Raspberry Pis, but you can try updating the OS using the older Raspberry Pi, then transfer the card to the new model. You can do this in the Terminal with:

sudo apt-get update
sudo apt-get upgrade
sudo apt-get dist-upgrade
sudo apt-get install raspberrypi-ui-mods

SD card issues

Make sure the SD card is completely formatted (not just a quick format), especially if you’re using NOOBS. Remember, it should be formatted as FAT32.  For most SD cards 32 GB and less, try using SD Formatter.  For SDXC cards that are 64 GB and larger, check out the Pi foundation's guidance on SDXC cards.

SD cards don’t last forever, so if a card is not working in your Pi, or on any other system, you may need to use a new SD card. You should also make sure the SD card is properly connected to the pins in the slot on the Raspberry Pi – it can’t be read it if it’s not connected properly!

Corrupt SD cards

Your Raspberry Pi’s problem may not be with the software, but with the hardware: your SD card might be corrupt. This can happen for many reasons, but the two most common causes are turning the Pi off repeatedly without running a proper shutdown, or writing a lot of data to the card. The latter you’ll only really experience in something like a server setup after a few years. The former can be avoided by using shutdown scripts, or using an OS that loads itself directly into the memory. Try piCore, a version of Tiny Core Linux.

Rainbows and lightning bolts

Seeing a rainbow block or lightning bolt in the top right- hand corner of your screen? This is the Raspberry Pi’s way of telling you that it doesn’t have enough power. Make sure your power supply can provide 2.5 amps for a Raspberry Pi 3 and 2 amps for any other Raspberry Pi model.

VGA adapter cable doesn’t work

The Raspberry Pi HDMI output does not provide a signal that can be used with a simple HDMI to VGA cable. Instead, you will need a proper converter like this one or this one.  

Pi 3 A+ or B+ works fine then stops working 

If you have a PI 3A+ or 3B+, that, after some days or weeks of working, suddenly has stopped booting, then please check if there is still 3V3 on the system. There have been some reports of the 3V3 supply suddenly stopping working, often after shorting the 3V3 to GND, but in a few cases also spontaneously. The issue is under investigation. To check for the absence of 3V3 measure on the 3V3 GPIO pin, (pin 1, see , the left most pin on the bottom row, indicated with an orange dot) with the red lead of your meter and with the minus lead touching the metal shield of either the USB ports, the Ethernet port, or even the HDMI port, as all of these are connected to GND. Set you meter to DC Volt. Make sure the probe you are measuring with does not slip, and simultaneously touches any of the other GPIO pins, as that might instantly destroy your PI, especially shorting the 3V3 pin to the 5V pin will prove to be fatal. If the 3V3 supply has disappeared, contact us for an RMA.

Raspberry Pi Support Forums

If all else fails, it is always best to head to the Raspberry Pi forums.

Before posting a question, you should always search the forum in case anyone else has experienced the same problem, and solved it. If not, drop a post in the most suitable place and the Pi community should give you a hand!