Boot loop on Galaxy S9 related to checking SD card

Since one of the last OS upgrades my Galaxy S9 has problems checking the SD card after booting. In most cases the launcher or the OS crashes/restarts, the screen turns black, only sometimes the SD card checking ends successfully and I can use the phone until the next reboot.

When I remove the SD card the OS can be used normally.

Is this a known problem, possibly a hardware problem?

How can I analyze further what’s causing the issue?

I feel this is not an immediate fit with your report … but … there is a recent unresolved thread where I went through some troubleshooting steps based on the idea that a corruption might have occurred due to a known SD card installation issue explained thoroughly here Conceivably (unlikely) even if you think you never used your card as “:warning: Formatted as internal storage” some software fault has occurred.

But simplest things first I would be inclined to try to test whether your SD card is (for unknown reason) reaching end of life. This does happen and would is simple to rule out.

In your place I would take out the SD card and check if it is readable on a PC. And re-confirm that the phone is ok without the card.
I would take the precaution to back the card up to the PC, in case the card should deteriorate.
I would buy or borrow a new or newly formatted SD card to check how the phone behaves with a known “clean” card.

Thank you for the quick reply!

The phone is working well without SD card so very likely it’s related to the SD card itself or an OS issue regarding SD card access.

It first happened after the phone ran out of battery (after an OS update) so I suspected that when the OS shut down due to low battery the SD card disk system was not released correctly.

However, after numerous automatic reboots the phone suddenly appeared fine again until the next manual reboot. So it even happened when I shut down the phone regularly which should release the disk (I’d expect).

Anyhow, I’ve ordered a new card and will try if it will have the same problem.

While doing the backup of the SD card currently on my laptop: the SD card is not encrypted, is it possible to encrypt the SD card with /e/?

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Unfortunately the new (Sandisk) SD card causes the same problem after I copied the data from the old card. This suggests that the issue is related to the files on the card.
Unfortunately no error message. Just the screen suddenly turns black, the “e” logo with the jumping dot appears, then the lock screen again. Then the screen turns black and the phone doesn’t react anymore.

Are there any log files that could lead to the problem cause?

Maybe you have some reason not to do this, but my tactic is to eliminate the possibility of “debris” … whatever, unknown … on the SD card. Should you possibly now have a clone of the old card “problem” I feel we are no further forward ?

How about format the new card back to FAT32 on the PC and try that ?

Of course there may be other approaches, but this seems simple. “Simple things first.”

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After deleting all folders on the card except the NextCloud files the problem was still there. Then I also deleted the NextCloud folder: and the problem was gone. This leads me to the conclusion that there is a possible denial of service attack by getting a certain file on an SD card. I don’t know what the SD card check does after booting the system.

Anyhow, let’s see if the problem will come back when I download the NextCloud files on the SD card again…

Thank you for all the suggestions!

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In case the problem should return you have two options to collect a logcat.

It is quite a good idea to practice collecting a log when there is no problem.

Should you chose to use the PC method, the output of one simple command

adb logcat -d > logcat.txt

will be very long.

For your purposes a suggested method would be to shutdown the phone.
Start the phone and find the earliest point you can launch the logcat.
Turn to the phone and do a task like start Files app and select a folder.
A moment after the Files operation has completed fully, close the logcat on the PC with ^C.

Use the help below to start to learn to read your output, search for E for Error, when you know there is no fault you will start to learn the sequence of an “all clear log”.

The larger part of the log will be the awakening. Try to get the hang of the time stamps to help you find any “event” that was recorded, like your opening of Files app.

adb logcat --help

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