I have searched and searched for an answer to this issue but am unable to find it. I have checked the boot thread on the main forums but with no luck.

I got a new 3B+, formatted an SDCard using Raspberry Pi imager from the website and wrote Raspberry Pi OS. The first time I did this it booted fine except for a power issue (faulty USB port). Changed the port and everything was good.

(To expand the power issue is fixed, I have the official plug adapter for Raspberry Pi so use that as well, same issue.)

Took the Pi home and then it wouldn't reboot, so I re-wrote the card, got a new card and wrote that tried several times and it booted once but then errored out, tried several more times and still nothing. Just a constant red light, the other light doesn't change.

Now, if I take said SD Card, put it in a USB to SD Card "reader"/"converter" and plug that into the Raspberry Pi, it will boot from USB.

Does this mean my SD Card port on the Raspberry Pi 3B+ is broken...am I missing something? I searched but couldn't find any similar issues.

  • Perhaps it is just a power issue. Need more detail of your set up.
    – joan
    Commented Aug 3, 2020 at 5:02
  • @joan Thanks for the comment. The red light (power button) is on constantly on the 3B+ so from what I have read it can't be a power issue. I have the official adapter as well. I have cut it down to power & HDMI out.
    – Tim
    Commented Aug 3, 2020 at 5:15
  • 1
    then errored out - in what way? If the green light does nothing at all you possibly broke the micro sd card slot on your pi ... possibly in transit when you Took the Pi home Commented Aug 3, 2020 at 7:35
  • @JaromandaX it booted but then there was an error in the boot cycle (unfortunately can't remember what). It never booted again after that, i.e. the green light does nothing unless I boot from USB.
    – Tim
    Commented Aug 4, 2020 at 0:59

1 Answer 1


It does sound like the SD card reader has gone pop.

I would:

  1. Format a spare card (less than 32Gb) using another Mac / PC as Fat (one partition)
  2. Create a small text file on this card using any editor - call it test.txt to check it accepts files OK
  3. Put this card in the on-board SD Card slot
  4. Install Raspberry Pi OS Lite on another card
  5. Put this card into the USB slot with your adapter
  6. Connect the screen and keyboard
  7. Power on the Pi and let it boot from the SD/USB adapter
  8. See if you can see the SD card in the PI

Try the command:

ls /dev/mmcblk0*

This should return:

/dev/mmcblk0  /dev/mmcblk0p1

The first is the card, the second is the partition created in step 1 above

Try also:

sudo fdisk -l

This should return disk details and you are looking for something along the lines of:

Disk /dev/mmcblk0: 7.4 GiB, 7948206080 bytes, 15523840 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x016ef04e

The above is an 8Gb card

If neither work I would say your onboard reader is damaged.

  • Thanks for this answer, @andyroo. I have tried this but unfortunately, there is nothing under /dev/mmc*. However, that was with a 128GB card I had laying around. I will try a 32GB card and soon. I will select yours as accepted answer. If the SD Card slot is so fragile, it probably means I cannot use the raspberry pi for what I need it for.
    – Tim
    Commented Aug 4, 2020 at 1:04

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